Inmates armed with mop handles and clubs held 15 guards captive at the maximum-security prison once known as Sing Sing, and face-to-face negotiations for the hostages' release got under way tonight.

The talks began without reporters whose presence the inmates had demanded, but a television network reporter and crew were later allowed into the cellblock.

State Sen. Ralph Marino, chairman of Committee on Crime and Corrections, emerged from a briefing with prison officials and said they were hopeful the hostages would be released "very shortly."

"They expect the hostages to be released one at a time," he said.

State corrections spokesman Lou Ganim did not reveal the prisoners' demands, but said they complained of a lack of recreation.

Marino said the prisoners' main demand seemed to be for an easing of overcrowding at the facility. Leaders of the uprising were also asking for amnesty, he said.

The inmates took control at 7:40 p.m. Saturday of a cellblock housing 618 men at Ossining Correctional Facility 30 miles north of New York City. No serious injuries were reported, although one guard was reported hurt by a blow to the head during the takeover and was released eight hours later.

This afternoon, an unidentified prisoner speaking through a loudspeaker said a inmates' committee wanted to meet with the prison administration and reporters.

"We don't wish to harm anyone," the man said, broadcasting his message to reporters on a nearby hill. "That would be our last alternative."

Inmates unfurled banners from broken windows saying, "We Don't Want Another Attica," a reference to a 1971 riot at New York State prison where 43 inmates and state employes died.

Inmates yelling out the windows demanded, "No negotiations through the warden" and shouted, "We live like animals in here."

Ganim said the uprising began when about 200 inmates were let out of their cells for a recreation period.

One inmate "didn't want to go down the hall to the recreation area," Ganim said, and shortly afterward an unidentified inmate started yelling and breaking furniture, touching off the melee during which the hostages were taken.

The inmates seized 16 corrections officers in the five-story Cellblock B, Ganim said. The injured guard was released at 3:30 a.m. today in return for prescription medication for 15 to 20 prisoners, he said.

The medication included antibiotics and epilepsy drugs, but no heroin, methadone or other hard drugs were given to the prisoners, officials said.

Late this morning, an inmate complaining of chest pains was carried from the cell building by four other inmates, who said "the hostages are safe and no harm has come to them," according to Ganim.

Ganim said the inmates were "a transient population," held for transfer to other state facilities. He denied overcrowding was a factor in the uprising, citing prisoner "idleness" as more of a reason.

In a statement released tonight, Gov. Mario Cuomo said, "The first priority is the lives of the 15 corrections officers."

But Cuomo warned that in such situations, potential hostages "would be endangered by any agreement that would unduly erode respect for the state's authority."

Ganim said the captured guards were not carrying guns and that the prisoners apparently had neither guns nor knives.

Ganim said prison officials spoke with one guard over the telephone this afternoon. The hostage said he was fine, Ganim said, and asked that electricity be turned back on in the cellblock. The request was granted.