A UN human rights envoy, who returned to Myanmar after a four-year ban on Monday, visited a Buddhist monastery raided by troops as he began an investigation into how many people were killed or detained in a crackdown on pro-democracy demonstrators, diplomats said.Paulo Sergio Pinheiro, the UN’s independent rights investigator for Myanmar, has said he is determined to gain access to the prisons and other sites to assess allegations of abuse by the ruling military junta.Diplomats said Pinheiro visited the Ngwe Kyar Yan monastery on Yangon’s outskirts, which was raided by troops in September, seeking to stamp out protests led by Buddhist monks.The abbot of the monastery, U Yawata, said at the time that 70 monks and lay disciples were taken away during the raid, one of many in which monks were beaten and hauled off in trucks by rifle-wielding soldiers. He said there were blood stains on beds as soldiers shot up the complex and stole gold.Pinheiro also met with officials at the Religious Affairs Ministry and the Home Affairs Ministry where he discussed his proposed visits to prisons. It was not immediately clear if he would be allowed to visit any detention facilities.He had given the junta a proposed itinerary before his five-day visit began on Sunday, but it was still being “fine-tuned,” said Aye Win, the UN spokesperson in Myanmar.“I hope I will have a very productive stay,” Pinheiro said after flying into Yangon, Myanmar’s largest city.Pinheiro has a history of prickly relations with Myanmar’s ruling generals. He abruptly cut short a visit in March 2003 after finding a listening device in a prison room where he was interviewing political detainees.Later that year, he accused the junta of making “absurd” excuses to keep political opponents in prison. He has been barred from the country since November 2003.