¶1*850Leonard J. Pugatch, Deputy Asst. Atty. Gen., Great Neck, N. Y. (Louis J. Lefkowitz, Atty. Gen., New York City, of counsel), for appellants Ward, Clement and Reid.
¶2William A. Babiskin, Rowley & Forest, P. C., Albany, N. Y., for Union appellants.
¶3Stephen M. Latimer, New York City (Emilio P. Gautier, Bronx Legal Services Corp., New York City, of counsel), for ap-pellees.
¶4Marjorie Mazen Smith, American Civil Liberties Union Foundation, New York City (Ruth Bader Ginsburg and Kathleen Willert Peratis, American Civil Liberties Union Foundation, New York City, Monroe H. Freedman, Bartel, Engelman & Fishman, New York City, of counsel), for American Civil Liberties Union, amicus curiae.
¶5Before KAUFMAN, Chief Judge, SMITH and OAKES, Circuit Judges.
¶7This appeal is from an order of the United States District Court for the Southern District of New York, Richard Owen, Judge, granting a motion for a preliminary injunction. The order prohibits state and union officials from assigning male correction officers to parts of the housing and hospital units of the Bedford Hills Correctional Facility (Bedford Hills), a women’s prison, pending a final determination of the action.
¶8In February, 1977, male correction officers were assigned to the housing units at Bedford Hills for tjie first time. This new assignment policy was an attempt by the Department of Correctional Services to eliminate sex certification in the assignment and transfer of correction officers1 and to implement the collective bargaining agreement between the State and the cor*851rection officers’ union.2 On April 1, 1977, appellees, women inmates at Bedford Hills, commenced this action against responsible state and union officials,3 alleging that assignment of male officers to the housing units deprived appellees of their constitutionally guaranteed right to privacy by causing them to be “involuntarily exposed” to the officers. In particular, appellees claim that the male officers are able to view them while they shower and perform other hygienic functions.
¶9Shortly after filing their complaint, ap-pellees moved for a preliminary injunction pursuant to Rule 65 of the Federal Rules of Civil Procedure. The motion was supported by the affidavits of four inmates specifying instances when their privacy rights allegedly had been violated by male guards. The state and union appellants submitted affidavits 4 and briefs in opposition to the motion in which they asserted among other things the need to conduct an evidentiary hearing to resolve disputed issues of fact. Joint Appendix for Appellants (JA) at 49a, 63a. On the basis of the affidavits and briefs alone, the court below determined that an evidentiary hearing was unnecessary and that the standards for granting a preliminary injunction were met. Forts v. Ward, 434 F.Supp. 946, 947-48 (S.D.N.Y. 1977). Accordingly, the district judge granted the appellees’ motion prohibiting state and correctional union officials from assigning male guards to those portions of the housing and hospital units which contain living quarters, toilets or shower facilities.5Forts v. Ward, No. 77-Civ. 1560 (S.D.N.Y. June 22, 1977) (order with notice of settlement).
¶10On this appeal, the State and the union attack the preliminary injunction6 on a number of grounds including the failure of the district court to conduct an evidentiary hearing.7 Because the briefs and affidavits present disputed issues of fact, we are compelled to reverse and remand the case to the district court for a prompt evidentiary hearing.
¶11It is well established that motions for preliminary injunctions should not be resolved on the basis of affidavits which evince disputed issues of fact. Normally, an evidentiary hearing is required to decide credibility issues. SEC v. Spectrum, Ltd., 489 F.2d 535, 540-41 (2d Cir. 1973); Dopp v. Franklin National Bank, 461 F.2d 873, 879 (2d Cir. 1972); Cerruti, Inc. v. McCrory Corp., 438 F.2d 281, 284 (2d Cir. 1971); Semmes Motors, Inc. v. Ford Motor Co., 429 F.2d 1197, 1204 (2d Cir. 1970); SEC v. Frank, 388 F.2d 486, 490-91 (2d Cir. 1968); SEC v. Petrofunds, Inc., 414 F.Supp. 1191,. 1196 (S.D.N.Y.1976) (Weinfeld, J.). Judge Kaufman has explained the rationale of this rule:
Generally, of course, a judge should not resolve a factual dispute on affidavits or depositions, for then he is merely showing a preference for “one piece of paper to *852another.” Sims v. Greene, 161 F.2d 87, 88 (3d Cir. 1947). This is particularly so when the judge without holding an evi-dentiary hearing, resolves the bitterly disputed facts in favor of the party who has the burden of establishing his right to preliminary relief. See id.1, 7 Moore, Federal Practice § 65.04[3], This caveat is most compelling “where everything turns on what happened and that is in sharp dispute; in such instances, the inappropriateness of proceeding on affidavits attains its maximum . . . ” Securities and Exchange Comm'n v. Frank, 388 F.2d 486, 491 (2d [sic] 1968) (Friendly, C. J.).
¶12Dopp v. Franklin National Bank, supra,461 F.2d at 879 (Kaufman, J.).
¶13Judge Owen determined that the motion raised no issues of fact requiring a hearing because none of the charges of privacy invasion contained in appellees’ affidavits was denied in appellants’ papers. 434 F.Supp. at 948. We must disagree. Our examination of the briefs and affidavits8 reveals several areas which deserve probing beyond the information contained in the vague, conclusory affidavits before the district court.
¶14In finding no issues of fact, Judge Owen focused on appellants’ failure to make an express denial of the “specific”9 charges made in the four affidavits.10 These vague allegations against unnamed officers at unspecified dates11 and times are impossible to verify, let alone deny, and *853the union appellants so asserted. Affidavit of Carl F. Gray sworn to on June 7, 1977, JA at 71a. It is hornbook law that a statement to the effect that one has insufficient knowledge “to form a belief as to the truth of an averment” is treated as a denial. Fed.R.Civ.P. 8(b); 5 C. Wright & A. Miller, Federal Practice and Procedure § 1262 (1969). The district court was in error, therefore, in concluding that none of these charges was denied in appellants’ affidavits and in accepting the truth of appellees’ general allegations.12
¶15Judge Owen’s decision to dispense with an evidentiary hearing was further based on appellants’ failure to submit affidavits challenging the truth of two allegations against named correction officers (the particularized allegations).13434 F.Supp. at 948. Undoubtedly, it would have been wise to submit affidavits from the named officers denying these two assertions. This omission, however, did not warrant the conclusion that ño issues of fact remained. First, the truth of one of these two allegations was suspect on its face, thereby alerting the reader of the need to test the affi-ant’s veracity.14 Second, appellants countered appellees’ complaint that the assignment of male guards caused appellees’ involuntary exposure and concomitant abridgement of privacy rights by asserting that appellees have the means to avoid these alleged deprivations.15 Accordingly, they argued, any exposure and resulting humiliation was of appellees’ own doing. Affidavit of Margery Evans Reifler sworn to on June 8, 1977, JA at 46a-48a; State Appellants’ Memorandum of Law in Opposition to Plaintiffs’ Motion, JA at 62a. Although we express no views on the merits of appellants’ argument, it certainly presents issues of fact and credibility which contradict appellees’ particularized and general allegations.16 The assertion that the inmates could control who observed them, and when, rebuts the contention implicitly made in all of appellees’ affidavits, and explicitly stated in their complaint, that exposure of their nude bodies was “forced” and “without their consent”.17 JA at 5a, *8549a. Thus, even if the basic facts were conceded, SEC v. Frank, supra, 388 F.2d at 490, the inferences to be drawn from them are in dispute. Consequently an evidentia-ry hearing should have been provided if practicable. Id.And this is hardly a case where an evidentiary hearing would have been impracticable due to the magnitude of the inquiry. SEC v. Frank, supra, 388 F.2d at 490-91; SEC v. Petrofunds, Inc., supra, 414 F.Supp. at 1196 n. 7. Nor would the taking of evidence have served little purpose. Herbert Rosenthal Jewelry Corp. v. Grossbardt, 428 F.2d 551, 554 (2d Cir. 1970); Redac Project 6426, Inc. v. Allstate Insurance Co., 402 F.2d 789, 790-91 (2d Cir. 1968); SEC v. Frank, supra, 388 F.2d at 490. There is no apparent reason for having denied appellees an opportunity to present and cross-examine witnesses. The facts are simple and the time consumed in an evidentiary hearing would be minimal. Resolution of the factual questions, most of which present credibility issues, with the benefit of cross-examination and the opportunity to observe the witnesses’ demeanor on the stand, is essential.
¶16Because of the important interests of the parties in both preventing privacy invasions and retaining work assignments, the district judge should conduct an evidentiary hearing on the preliminary injunction motion as soon as convenient, but no-later than December 15, 1977.18 We suggest that the district judge consider consolidating the trial on the merits with the evidentiary hearing pursuant to Rule 65(a)(2). Fed.R.Civ.P. 65(a)(2).
¶17Reversed and remanded.