BEIJING - China has detained scores of Buddhist monks over the past month, a Tibet activist group said Wednesday, a day after six monks were sentenced in the first trial of rioters since deadly violence in Tibet last month.

The International Campaign for Tibet said more than 160 people were detained from several monasteries in the Tibetan capital of Lhasa and neighboring provinces during April.

Authorities removed at least six monks from the Nechung monastery, eight from the Nalanda monastery and rounded up at least 60 people, including monks from the Pangsa monastery, the Washington, D.C.-based group said in a six-page statement.

The group also said up to 100 monks were detained at the Rongwu monastery in the neighboring province of Qinghai.

The U.S.-government funded Radio Free Asia also reported that two nuns in Sichuan province were detained for protesting.

There was no way of independently verifying either the activist group's claims or the radio report. The International Campaign for Tibet said it received its information from Tibet sources but did not provide more details.

Their reports follow mass anti-government riots and protests in Lhasa last month. The riots and subsequent crackdown by Chinese authorities have drawn worldwide attention to China's human rights record and its rule in Tibet ahead of August's Beijing Olympics.

On Tuesday, a Chinese court in Lhasa sentenced 30 people, including six monks, to jail terms ranging from three years to life for their involvement in the Lhasa riots on March 14.

Three of the people were given life sentences, including a Buddhist monk identified as Basang who led 10 people to destroy local government offices, burn down shops and attack policemen, the official Xinhua News Agency said.

The other two men given life sentences -- a driver and a businessman -- were convicted of inciting others to commit arson and loot shops during the riots, Xinhua said.

New York-based Human Rights Watch condemned the one-day trials in Lhasa, saying the defendants "were tried on secret evidence behind closed doors and without the benefit of a meaningful defense by lawyers they'd chosen."

"Guilty or innocent, these Tibetans are entitled to a fair trial," Sophie Richardson, Asia advocacy director at Human Rights Watch, said in a statement Wednesday.

The speedy trials are one sign that China is attempting to wrap up the punishment phase of its latest campaign to assert control in Tibet.

China has said 22 people died in the riots, while Tibet's government-in-exile said Tuesday it believes at least 203 Tibetans were killed in the ensuing crackdown.

The estimate was compiled from a combination of the government's own sources, Tibetan exile groups and official Chinese media. It was impossible to independently verify the information.

But in a sign that the unrest was continuing despite the government pouring thousands of security officials into Tibetan areas, Xinhua reported late Tuesday that a policeman and an alleged "riot leader" were shot dead during an attempted arrest in northwestern Qinghai Province.

Xinhua said police moved to arrest the suspected riot leader Monday after a monthlong investigation into a riot on March 21. He resisted and was killed by other officers in a gunbattle, it said.