YANGON, Myanmar — A leading dissident on the run since escaping a crackdown by government thugs two months ago and a Buddhist monk who helped spearhead recent pro-democracy demonstrations have been arrested, exiled activists and an official said Tuesday.

The dissident, Su Su Nway, was detained Tuesday as she tried to put up the leaflet near a Yangon hotel where a visiting U.N. human rights investigator has been staying, said the official, who insisted on anonymity because he is not authorized to speak to the press. Stanley Aung, of the dissident National League for Democracy-Liberated Area Myanmar in neighboring Thailand, confirmed her arrest.

Aung said dissidents arriving at the Thai border also confirmed the arrest of U Gambira, a leader of an alliance of monks established to support pro-democracy protests after small demonstrations began in August.

Other dissident groups also reported U Gambira's arrest, though details differed. Some said he had been arrested on Nov. 4, the same day he had an article published in The Washington Post in which he vowed to continue the struggle against the country's military regime.

Su Su Nway was active in protests in Yangon in August against an oil price hike and dramatically escaped arrest when a demonstration was crushed on Aug. 28. Video filmed at the time and broadcast around the world showed her comrades protecting her as the pro-government thugs tried to pull her away.

The September demonstrations, which attracted as many as 100,000 people at their height, grew out of the smaller August protests, which were attended by a relative handful of political activists such as Su Su Nway.

The U.N. investigator, Paolo Sergio Pinheiro, arrived Sunday on a five-day visit to investigate human rights conditions in the wake of September's violent crackdown by the ruling junta.

The government acknowledged detaining almost 3,000 people in connection with the protests, but says it has released most. Most of the prominent political activists who were arrested remain in custody.

After the Aug. 28 confrontation, Su Su Nway, 35, said she had a heart condition and could not take part in street demonstrations, but wanted to show solidarity with other prominent activists in jail.

Since then she has been in hiding, but there have been reports of her occasionally surfacing for more protest activity. She had regular contact with the media until her mobile phone was disconnected early September.

The Democratic Voice of Burma, a Norway-based radio station run by Myanmar dissidents, reported that on Oct. 27 she laid lay flowers at the spot where Japanese video journalist Kenji Nagai was shot dead by government security forces while covering the demonstrations in Yangon a month earlier.

Su Su Nway served nine months in prison in 2005-2006 for her labor activism when she was convicted of defamation after she won a conviction against four officials for using forced labor.

She is also a member of detained opposition leader Aung San Suu Kyi's National League for Democracy party.