A PHUKET man who extorted money from construction contractors by posing as a policeman and an army officer also had three illegal handguns, police say.

The man, Samrid Patanon, 45, was arrested in a raid on his Thalang home about 7pm on Wednesday, with governor's volunteers helping police.

Khun Samrid, who also used the name Sommai, was in possession of ID cards as both a senior policeman and an officer in the Thai Army's most feared unit, the Internal Security Operations Command.

He told managers on sites that he was working on behalf of ''the local authority'' and produced one of the cards to support his claim.

Police are holding him at Cherng Talay while they determine how much money he managed to extort from construction companies while operating his alleged scam.

Officers say Khun Samrid would wait to hear when a crackdown was underway against illegal Burmese laborers, then visit construction sites and demand 3000 baht for each Burmese worker.

His plan fell apart when one of his would-be victims went to complain to the Provincial Hall headquarters of Phuket Governor Wichai Praisa-ngob about the extortion by a ''local authority.''

Police quickly became involved and Wednesday night's arrest is believed to have ended the scam. Three police radios were also found in Khun Samrid's possession.

The Army's ISOC section has been blamed for organising the secret ''pushbacks'' from Thailand's Andaman coast of Rohingya boatpeople from Burma and Bangladesh during the high season of 2008-2009.

Hundreds of would-be refugees died at sea before Phuketwan and the South China Morning Post newspaper in Hongkong exposed the inhumane practice.