The migrants were found on a rubber plantation in Takua Pa district in the southern coastal province of Phang Nga, district chief Manit Phianthong told AFP.

"We got a tip-off from an informant that a trafficking gang would be transporting Rohingya people to Malaysia," he said, adding that the migrants came from Myanmar's western Rakhine state and Bangladesh.

Thousands of Rohingya -- a Muslim minority group not recognised as citizens in Myanmar -- have fled deadly communal unrest in Rakhine since 2012, mostly heading for Malaysia.

The migrants arrested on 11th October were ferried onto the Thai mainland from a small island in the Andaman Sea, Manit said, adding that one of the arrested traffickers confessed he was part of a bigger gang.

"We are still looking for the real masterminds," said the official.

Twelve Rohingya migrants are thought to have escaped during the raid, he added.

Myanmar views its population of roughly 800,000 Rohingya -- described by the United Nations as one of the most persecuted minorities in the world -- as illegal Bangladeshi immigrants, and denies them citizenship.

They face travel restrictions, forced labour and limited access to healthcare and education.

Around 300,000 Rohingya have over the years gone to live in Bangladesh, which recognises only a small portion as refugees and regularly turns back those trying to cross the border.

Rights groups say the stateless migrants often fall into the hands of unscrupulous people traffickers.

They have also criticised Thailand in the past for pushing boats of Rohingya entering Thai waters back out to sea and holding migrants in overcrowded facilities.

Thailand said last year it was investigating allegations that some army officials in the kingdom were involved in the trafficking of Rohingya.