The Chinese police have launched a manhunt for 88 suspects who were 'heavily involved' in the riots that shook Tibetan capital Lhasa last month, during the anti-government protests spearheaded by monks.

Eighty two people had been arrested but another 88 were still at large, a senior official of the Lhasa Public Security Bureau said, as China continued its crackdown to quell the simmering unrest.

The strongest and most sustained anti-government protests in the last 20 years have left 20 people dead, a toll figure the Tibetan groups dispute and put at 150.

Till date, 365 suspects in the Lhasa riots had surrendered to the police, of whom 328 had been set free because of minor nature of their offences and willingness to cooperate in the probe, Bureau Vice-Director Jiang Zaiping said in Lhasa.

He claimed that most of the suspects had pleaded guilty and said they were pressured into getting involved in the riots.

China had claimed two days ago that the police had seized guns and explosives from 11 monasteries in the Tibetan-populated prefecture of Gannan in Gansu province.

Officials had said that 519 monks had surrendered to the police following violence in Gannan, but 413 had been released as they were found to have committed only minor offences.

Days before, Chinese police had detained nine monks, whom it accused of having exploded a homemade bomb in a Tibetan township government building, during anti-government protests at Gyanbe in Qambo prefecture.

Authorities had announced that Tibet [Images] would be reopened to tourists from May 1 but it remains uncertain with reports that the date has been deferred.

Tibet has remained out of bounds for journalists, though a group was taken recently on a government-controlled trip to Lhasa, two weeks after the riots broke out.