KHEK NOI: The Thai army on Monday began the forcible return of thousands of ethnic Hmong asylum-seekers to communist Laos despite international protests over fears they could face persecution.

A force of around 5,000 entered the camp in Huay Nam Khao village in northern Thailand before dawn, to round up more than 4,000 Hmong being held there, said Colonel Thana Charuvat, co-ordinator of the repatriation.

By early afternoon around 2,000 Hmong had been driven from the camp in trucks, according to an AFP photographer at an army centre in Khek Noi village, about 12 kilometres (seven miles) from the camp in Phetchabun province.

Media were not allowed beyond the centre, where Thana told reporters that the operation was expected to take one day.

The group are seeking asylum in Thailand claiming that they face persecution by the Laotian regime for fighting alongside US forces during the Vietnam War and human rights groups have warned they could resist the expulsion.

"Around 2,100 of them are co-operating with the move. The army is talking with the rest," Thana said.

But Prime Minister Abhisit Vejjajiva told reporters in Bangkok that the repatriation was "going well".

"There was no resistance," he said.

Thailand says they are illegal economic immigrants, but has come under fire from the international community for refusing to grant the UN Refugee Agency access to them to assess whether any are political refugees.

As the deportation began, the United States said it "strongly urges" Thailand to suspend the operation.

"We deeply regret this serious violation of the international humanitarian principles that Thailand has long been known for championing," State Department spokesman Ian Kelly said in a written statement.

Colonel Thana said the group would be removed from the Huay Nam Khao camp by truck and later transferred to 100 buses that carry 40 people each.

"They will be transported from the camp to the army camp in Lom Sak district (in Phetchabun) before moving to immigration in (the border town of) Nong Khai and going to Laos," he said.

Earlier security forces were seen heading towards the camp by truck armed with batons and shields, although the army said it would not use violence.

Special forces members were among the troops entering the camp and 50 mobile prison trucks also arrived there last night, said Sunai Phasuk, a Thailand analyst at New York-based Human Rights Watch.

"The army said they would first target group leaders and potential trouble makers. Those people would be snatched and sent out first," he told AFP.

He said local officials expected the Hmong to resist deportation attempts, warning that the situation could "turn ugly".

Thailand has promised the Lao government that they would be sent back by the end of the year and says Laos has assured them the group will be safe after returning.

"The Lao government confirmed that they will give amnesty to the Hmong leaders," Colonel Thana said.

But diplomats have said several hundred Hmong could have valid fears of persecution and as such should not be forcibly returned. Related article: US 'deeply' regrets Hmong deportation

"It seems difficult to imagine there will be fully fledged international access to the Hmong community on arrival, given the past experiences of repatriation," a Western diplomat in Bangkok said Sunday.

Laotian foreign ministry spokesman Khenthong Nuanthasing said they were "preparing to receive them from this afternoon". Related article: Expelled Hmong's decades-long neglect

The returnees are due to be sent to the central province of Bolikhamsay, where they will be placed in temporary shelters, he said, adding: "We must first determine where they want to go".

Eric P. Schwartz, US Assistant Secretary of State for population, refugees and migration, made a last-ditch offer Sunday to help Thailand take an alternative path.

"We have made it abundantly clear that we are prepared to roll up our sleeves and work with partners in Thailand for a solution that is humane and responsible. Even at this late date we're fully prepared to do that," he told AFP by telephone from the United States.

Antonio Guterres, the head of the UN refugee agency, urged Thailand on Thursday to call off the expulsions, saying they would "set a very grave international example".