File picture: Matt Rourke/AP Photo.

Bangkok - Twelve people arrested earlier this week for sharing a Facebook post about the alleged rape of a British tourist have been charged and bailed, their lawyer said Friday.

The 12 individuals have since Tuesday been hauled down to the tourist island of Koh Tao after allegedly sharing a post detailing the woman's allegations and criticising local police.

The 19-year-old UK national, who has since returned home, told British media that she was drugged and raped while holidaying on the island. 

Her account has been disputed by Koh Tao police, who say a rape complaint was not formally filed. 

Winyat Chatmontree of United Lawyers for Rights and Liberty told AFP the 12 hailed from all over the country, including the capital Bangkok. 

"They were accused of sharing false information," Chatmontree said.

Charged under Thailand's Computer Crimes Act, the group were accused of "committing together the crime of disseminating, broadcasting, and sharing false information," he said.

They were all released on Thursday night on a bond of 60,000 baht ($1,830) each.

They face up to five years in prison if found guilty, said Chatmontree.

Arrest warrants have also been issued against the administrators of two public Facebook pages which shared posts about the alleged rape, said deputy tourist police chief Surachet Hakpan. 

Neither of the people sought are in Thailand, he added.

Thailand's Computer Crimes Act is a broadly worded law which forbids uploading "false data" online. 

Critics say the law has been used to stamp out dissent and curb free speech. 

The case against the 12 had the potential to justify further prosecutions against social media users in Thailand, said Pornpen Khongkachonkiet, director of the advocacy group Cross Cultural Foundation.

"It is a serious precedent that is getting worse and worse in affecting our freedom of expression," she said.

While Thailand's southern islands are considered safe and popular tourist destinations, several high-profile incidents have tarnished their reputation in recent years. 

In 2014, the battered bodies of two British backpackers were found on the beach in Koh Tao.

Two Myanmar migrant workers were sentenced to death for the murders after a controversial investigation and trial that were criticised by observers and a family member of one of the victims.