NAIROBI, Kenya — The military government of Sudan has imprisoned and tortured hundreds of opposition figures, hanged prisoners after brief show trials, and used live ammunition on demonstrators in pursuing an "exceptionally cruel and intolerant" policy of repression, an international human-rights group has charged.

The report by London-based Africa Watch supports increasing indications that the military government of Lt. Gen. Omar Hassan Ahmed Bashir, which seized power last June 30, is perhaps the most brutal to have afflicted Sudan in its 34 years of independence.

"In a mere nine months since its seizure of power," the report states, "the Revolutionary Command Council has . . . embarked upon a systematic and brutal repression of political opposition in Khartoum which already surpasses even the worst excesses perpetrated by Numeiri."

Jaafar Numeiri was the Sudanese dictator overthrown in a popular revolution in 1985, amid increasing famine, war and an attempt to impose a fundamentalist Islamic state on this heterogeneous country.

The Africa Watch report comes as the government's international friends are rapidly dropping away. At the end of February, the United States, which had been an ally of the previous democratically elected government, cut off an estimated $60 million in aid. The reason was that federal law prohibits continuing aid to unelected governments that overthrow democratic regimes without establishing a timetable for new elections.

Several other major international donors to Sudan, including Britain, the Netherlands, France and West Germany, have also scaled back their aid programs. Among the Bashir regime's few remaining friends is Libya, which is said to have stepped up its sale of petroleum to the regime. After returning to Khartoum from a recent visit to Libya, Bashir announced new plans for a Libyan-Sudan federation to be formed over the next four years.

More recently, possibly in response to growing international criticism, the Bashir regime has announced the freeing of 21 trade unionists held in prison for as long as nine months. The government also said it would shortly release all other political prisoners except those charged with corruption, a caveat that Africa Watch charged is so broad that it could cover most prisoners otherwise considered political detainees.

The government also said that long-delayed visits by families, friends and diplomats would be permitted prisoners after the end of the Muslim holiday of Ramadan, or after the end of April.