BANGKOK: Rights groups and diplomats have expressed deep concern that Thailand will deport 4,000 ethnic Hmong held in the northeast back to communist Laos, where they fear persecution, by the end of the year.

Thai authorities have reportedly deployed extra troops to Phetchabun province where most of the Hmong are held in camps, fuelling fears that they will fulfil a pact with Laos to expel the group before 2010.

Thailand has also failed to renew an agreement, which expires on December 31, with the only aid group providing assistance at the camps.

"It is shocking that the Thai army is now trying to use the Christmas and New Year holidays to push back more than 4,000 Lao Hmong, many of whom have escaped from political persecution, rights abuses and fighting in Laos," said Sunai Phasuk, a Thailand analyst at Human Rights Watch.

"This is brazen contempt for the most basic principle of refugee law."

The ethnic minority Hmong in Phetchabun are seeking political asylum, claiming they face persecution from the regime in Laos because they fought alongside US forces during the Vietnam War.

On Tuesday diplomats in Bangkok met Thai Foreign Minister Kasit Piromya to voice their concerns about the imminent deportation of the Hmnong, said Liselott Agerlid from the Swedish embassy, on behalf of the European Union.

She said they were "particularly concerned" that another group of 158 Hmong held in Nongkhai province, who have already been screened and granted UN refugee status, could be sent back to Laos.

This group has been offered resettlement in Western nations that Thailand has refused to allow, although large numbers of Hmong have been resettled in the past, notably in the United States.

After the meeting Kasit's secretary, Chavanond Intarakomalyasut, told AFP the repatriation to Laos "is our policy, but how to do it and when will be discussed."

Thailand says the thousands in Phetchabun are economic migrants, and has refused access for the UN refugee agency (UNHCR) to assess if any are in fact refugees according to international criteria.

"We understand that the Thai government's own screening process found a number of people had international protection needs, which means they may well qualify to be refugees," said UNHCR spokeswoman Kitty McKinsey.

"We have long maintained no one with a valid international protection claim should be returned to Laos on anything but a voluntary basis."

A Western diplomat in Bangkok told AFP they suspected several hundred would be classified refugees if properly screened, adding that there was a "sense of urgency" in the international community about the deportation.

"We have reports that in the last few weeks there has definitely been an increase in the deployment of troops. Previously we didn't think that they had the capacity or the readiness to do this."

Aid group Medicins Sans Frontieres (MSF) in May pulled out of a camp in Phetchabun, accusing Thailand of trying to repatriate the group forcibly.

MSF said the Hmongs recounted killings, gang-rape and malnutrition inflicted by Laotian forces, but Laos foreign affairs spokesman Khenthong Nuanthasing on Tuesday denied there was any harassment of the minority in Laos.

"According to the agreement between the two countries, the 4,000 Hmongs should be sent back to Laos. But we are waiting for the decision of the Thai government," he added.

The only aid group now active in Phetchabun is the Catholic Office for Emergency Relief and Refugees, supported by the UN Children's Fund (UNICEF), which said their agreement to provide help runs out at the end of December.

"We have been seeking arrangements to be made after this month but so far we haven't received feedback from the government," said UNICEF Thailand representative Tomoo Hozumi.

Sunai of Human Rights Watch called on Thai Prime Minister Abhisit Vejjajiva to make an emergency intervention to prevent the deportations.

"Thailand risks sullying its reputation to allow the army to carry out this immoral and unlawful policy," he said.