Prince George's County jail director Arnett Gaston gave county elected officials a nine-page report yesterday describing the improvements he made during his term as jail director and disputing a number of points that were in a series of newspaper articles about sexual assaults and rapes in the jail.

In the report, Gaston said that he is sensitive to the problem of rapes and sexual assaults in the jail. But he expressed doubts as to whether a number of the rapes and sexual assaults described in the Washington Post series actually occurred, saying that a majority of those who "participated in sexual assaults in our jail" had "mental problems" and that two of the victims were homosexual.

"Among the group of 12 victims were two admitted homosexuals and also an individual with a family history of sexual and physical abuse spanning two generations," Gaston wrote in his report. "This is not to say that all of these people presented in the articles imagined or fantasized assaults but, given this situation, some weight must be given to the possibility of these factors impacting on real, imaginary or consentual activity."

In the series, all of the victims' accounts of sexual assaults were corroborated, in most cases by statements from men who said they had sexually assaulted or raped them, and also, in a few cases, by medical evidence. The rapists and most of their victims were named.

Gaston did not say exactly how many sexual assaults and rapes he believes occur in the jail each year, although he said that an estimate by guards and inmates of 12 a week is an exaggeration. He said, however, that the sexual assault and rape problem in the county jail is "no worse" than the rate reported in a recent study of federal prisons. The study, by Peter and Thomas Kane, reports that "about two of every 100 inmates must defend himself against sexual assault and less than one of the 100 is actually victimized," according to Gaston's report.

Nearly 15,000 inmates each year spend time in the county jail, although at any one time there are between 425 and 500 inmates. According to guards and inmates, conditions in the jail are worse than in many federal prisons. Those vulnerable to sexual assault -- men awaiting trial on misdemeanor charges -- often are in the same sections with those charged with violent crimes, who tend to rape other men.

The report also describes 12 improvements that Gaston made at the jail since he was appointed jail director three years ago by County Executive Lawrence J. Hogan. They include "upgraded and expanded" health care, a security fence and lights outside the jail, a work detail program so that certain inmates can work outside the jail on county projects, a furniture restoration program for certain inmates who repair county furniture, and the establishment of an internal affairs unit to investigate all complaints of sexual assaults and rapes.

In addition, Gaston described several improvements that he said will lessen or have lessened the likelihood of sexual assaults and rapes occurring in the jail. They include construction of a temporary housing unit that will be opened in a few days to house 100 inmates charged with minor crimes; the employment of guards who have completed the training mandated by state law; and increasing the staff of the jail by 30 percent, from 173 to 228, since 1979.