BANGKOK (AFP) - Thailand and Cambodia agreed on Tuesday to quash "rumours" of a crackdown against illegal migrant workers by the new Thai junta after the exodus of nearly 180,000 Cambodian labourers.

The numbers of labourers fleeing home soared after the Thai military regime warned last week that illegal foreign workers face arrest and deportation.

The junta has since insisted there is no "crackdown" and blamed false rumours for the exodus.

The International Organisation for Migration has previously estimated that around 180,000 undocumented Cambodian workers live in Thailand, so it is unclear exactly how many still remain.

Migrants from neighbouring Cambodia, Laos and Myanmar play a key role in Thai industries such as seafood, agriculture and construction, but often lack work permits.

"We need to work closely together to allay fear among the Cambodian labourers in Thailand that it is not the policy of the current administration to crack down on labourers regardless of their (legal) status," said Cambodian Ambassador to Thailand Eat Sophea.

She also dismissed rumours of the shooting and abuse of Cambodian migrants by the Thai authorities - among the factors believed to be triggering workers to flee.

"The reports about shootings, the reports about other abuses are rumours and are not true, it's been taken out of context. We agreed to work together in order to clarify any issues," Mr Eat said.

During talks with Thai Foreign Ministry Permanent Secretary Sihasak Phuangketkeow on Tuesday, the two countries also agreed to set up a hotline on labour issues.

"We agreed to set up some form of a hotline... to communicate requests for clarification for assistance to facilitate those labourers who wish to return to Cambodia," the Cambodian ambassador said.

At the main border crossing between the two countries in Poipet - a bustling town home to several large businesses, casinos and hotels - a few hundred Cambodian migrants arrived in Thai military trucks and police cars on Tuesday morning.

"The number of Cambodians returning from Thailand into Poipet (the main Thai-Cambodian border crossing) in just over a week reached 157,000 by this morning," said Mr Kor Sam Saroeut, governor of the north-western province of Banteay Meanchey, where the checkpoint is based.

Around 20,000 others have crossed the border at O'Smach, a checkpoint some 250km north-east from Poipet, according to the governor and a senior Cambodian police official.

Thailand's military regime has denied it has been forcing Cambodian workers out of the country after issuing a warning last week that it viewed illegal migrants as a "threat".

The Foreign Ministry has said the authorities attach "great importance" to the role migrant workers play in Thailand's economy.

In the past, the Thai authorities have turned a blind eye to illegal labourers because they were needed when the economy was booming.

But now the country is on the verge of recession after the economy contracted 2.1 per cent quarter-on-quarter in the first three months of 2014.