ATLANTA (AP) _ The U.S. government is releasing five times as many Cubans from prison each month as it did before riots in two federal lockups last year focused attention on the detainees' efforts to remain in this country, a published report says.

Since Dec. 4, when Cuban prisoners and U.S. negotiators signed an agreement ending an 11-day siege at the U.S. Penitentiary in Atlanta, the number of Cubans freed has gone from about 20 a month to about 100 a month, said a report in Sunday's combined editions of The Atlanta Journal and The Atlanta Constitution.

During the same period, another 1,200 were approved for release by the Immigration and Naturalization Service - although most of those had been already designated for release before the riots in Atlanta and Oakdale, La., the newspapers said.

''The majority of these people are going to be paroled,'' said Randy Levine, associate deputy attorney general in the U.S. Justice Department. ''We're trying to move these people out as quickly as we can.''

However, the newspapers said that Justice Department officials have indicated that loopholes in the agreements that ended the riots could lead to prosecution or deportation of the leaders of the uprisings.

FBI agents across the nation have been gathering accounts of the two prison riots for a report expected to be completed next month, the newspapers said.

Justice Department spokesman Patrick Korten said federal authorities, in finalizing the agreements ending the riots, were careful not to rule out prosecution.

''Anybody who we can determine took action that threatened lives would be a serious target for prosecution,'' he said.

Critics of the government's dealings with the Cubans said prosecution would violate the spirit of the agreements.

''They are treating the agreements like legal papers instead of moral covenants,'' said Ralph Penalver, the lawyer for Miami's Auxiliary Bishop Agustin Roman, who participated in the talks that led to the agreements.

''The U.S. Justice Department requested that the bishop use his moral authority to end the worst prison riots in history. In this situation, I think the government has a very special responsibility to provide procedural safeguards, letting the law be their guide, but justice their goal,'' he said.

Nearly 1,000 detainees rioted Nov. 21 in Oakdale, taking 28 hostages and surrendering Nov. 29. In Atlanta, some 1,500 detainees took over the prison before surrendering. There are about 3,800 detainees nationwide.

Agreements ending both seiges also promised individual reviews for the detainees, who were among 125,000 Cubans to come to the United States during the 1980 Mariel boatlift.