BANGKOK (AFP) - UN envoy Ibrahim Gambari was due in Bangkok on Sunday for an Asian tour aimed at building pressure on Myanmar's generals, who have shrugged off international concerns and arrested more protesters.

Seasoned UN trouble shooter Gambari is expected to prepare the ground for a return visit to Myanmar following his mission there last month, which was aimed at defusing a crisis sparked by a deadly army crackdown on protests.

He was allowed to meet with both junta chief Than Shwe and detained democracy leader Aung San Suu Kyi, but the junta's pigeon steps toward reconciliation appeared to be stuttering over the weekend.

Human rights watchdog Amnesty International reported on Sunday that six dissidents were arrested in Yangon in the early hours of Saturday morning. It had previously said that four key activists were held.

About 1,000 people remain in custody at unknown locations in Myanmar since last month's rallies, and concern is growing for their safety.

Buddhist monks led up to 100,000 people onto the streets of Yangon in September, but the subsequent government crackdown left at least 13 people dead and saw more than 2,000 arrested.

They were the biggest protests against military rule in Myanmar, previously known as Burma, since a 1988 democracy uprising.

Myanmar's military rulers on Saturday announced that a night-time curfew had been eased, but security forces continue to comb through Yangon's neighbourhoods, rounding up people linked to the pro-democracy protests.

Amnesty said the six activists recently held included Htay Kywe and Mi Mi, who led some of the first rallies against the regime in mid-August, and said they were at "grave risk" of torture and ill-treatment.

"Continued arrests fly in the face of the promises made this week by the Myanmar authorities to cooperate with the United Nations," the group said in a statement on Sunday.

The UN Security Council on Thursday issued a statement deploring the regime's crackdown. It urged the junta to hold talks with the opposition led by Nobel peace laureate Aung San Suu Kyi and release political prisoners.

Myanmar's official media has labelled the statement "regrettable," but said it would cooperate with the world body while pressing ahead with its so-called "road map" to democracy.

It made no acknowledgement of the UN call for the release of political prisoners nor for it to hold dialogue with Aung San Suu Kyi.

Gambari will likely be keen to harness support to push the regime towards democratic reform, said Debbie Stothard of advocacy group the Alternative ASEAN Network on Burma, but warned that the junta appeared indifferent.

"Even now as all these diplomatic efforts are taking place, the regime continues to crack down very viciously against activists and monks and even journalists," she told AFP.

"So the toll of detentions and deaths seem to be increasing, even as Gambari is flying around looking for diplomatic support."

Gambari will first to go to Thailand, where he is due to arrive late Sunday, before heading to Malaysia, Indonesia, India, China and Japan. He is hoping to return to Myanmar in his two-week tour.

Since Gambari's last visit, Than Shwe has made a heavily conditioned offer to hold talks with Aung San Suu Kyi, hinged on her ending support for sanctions and dropping "confrontational" policies.

He also appointed deputy labour minister Aung Kyi as a liaison officer tasked with coordinating contacts with the Aung San Suu Kyi.

Myanmar's state press on Sunday made no mention of the envoy's Asia tour, instead publishing accounts of pro-government rallies.

Tens of thousands of people were taken Saturday to a junta-sponsored rally in Yangon in a show of strength by the generals.