A police investigation has been launched into an allegation that five policemen in Kalasin province abducted a woman, falsely accused her of drug possession and extorted 50,000 baht from her in exchange for her release.

The allegation is backed by a video taken secretly with a mobile phone.

All five men in the video were police attached to various units in Kalasin province.

An investigation was launched after the woman turned to Khaosan Palanchai Facebook page for help. TV Channel 8 then sent a news team to see her, and the alleged extortion by the police officers was widely reported.

The woman, whose name was withheld, alleged that five men stormed into the Kalasin resort where she was staying alone around 6.20pm on July 4.

The men claimed to be members of a police task force. They searched her room but found nothing illegal. They then took her from the room and asked her to point at some white tissue paper left under a tree outside the room, but she refused, the woman said.

Those men had wanted to record a video of her pointing at the tissue paper, as evidence.

She was then forcibly taken to their vehicle and they drove around Muang district. On the way, they had tried to persuade her to confess that she owned the tissue paper, which contained drugs. She said that she refused.

The five men demanded 50,000 baht in exchange for her release, the woman said.

She said she was afraid of being falsely charged with drug offences. She contacted her younger brother and borrowed 30,000 baht from him, which she then gave to the men along with 20,000 baht they had seized from her room.

She had managed to video what happened during the police raid on her room without them noticing.