Two female hostages were released unharmed Friday by the two inmates who took them hostage. The prisoners had demanded to meet with reporters over conditions at the overcrowded Wyoming State Penitentiary.

Abdula Amin, 37, and Don Calkins, 25, surrendered about 5:40 p.m., prison officials said.The two inmates, wielding makeshift knives, took Barbara France and Betty Lewis hostage shortly after 7 a.m., during sick call in the prison's maximum-security unit.

The inmates, both serving sentences for sexual assault convictions, had tied themselves to the women with rope, said Warden Duane Shillinger.

The prisoners had demanded a press conference or to discuss their grievances with the press, said Gary Sherman, executive secretary of the state Board of Charities and Reform.

Prison officials, including an FBI-trained negotiator, spoke with the inmates by telephone through the day Friday, but Shillinger said any demands beyond those for food would not be granted unless the women were released.

Reporters from Wyoming and Colorado flocked to the penitentiary in the afternoon, but prison officials kept their presence secret from the inmates.

Photographers and television camera operators were prevented from taking pictures.

Shillinger said the inmates were told they could hold a news conference if they wish, but only on the condition that they release the two women.

The inmates kept their captives in a counseling room. Sherman, who said the inmates had homemade knives, said the rest of the penitentiary had been locked down.

"Everybody is very concerned and cautious and worried," he said. "The only thing we don't have control of is the safety of those two hostages."

Associate Warden Al Urie said Amin began serving an eight- to 20-year sentence on a conviction of first-degree sexual assault and a life term for a habitual offender conviction in December 1983.

Calkins began serving an eight- to 15-year sentence on two convictions of first-degree sexual assault and aggravated burglary in April 1985.

Neither man had created major problems at the prison in the past, Urie said.