Rights organisation says Thai soldiers and police torture detainees using techniques such as waterboarding, smothering with plastic bags and electric shocks.
International human rights group Amnesty International (AI) on Wednesday accused Thailand's military government of allowing a "culture of torture" to flourish since the army seized power in a 2014 coup.
The military took power in Southeast Asia's second-biggest economy after months of protests against a populist government, saying it had to step in to prevent violence and restore order.
Two Amnesty International staff were scheduled to speak on Wednesday at the Bangkok launch of a report detailing 74 cases of alleged torture at the hands of Thai soldiers and police. The advocacy group was told speaking at the event would be cause for legal action, Amnesty International Media Manager Asia Omar Waraich said.
"The authorities said to us that [...] if any representatives from Amnesty International spoke at the event they would be in violation of Thailand's labour laws," he said. "They did not specify further."
'Culture of torture'
In a report provided to Thai authorities before the conference, Amnesty International had documented 74 cases of alleged torture at the hands of soldiers and police. The report also dealt with post-coup decrees which allowed authorities to detain people incommunicado.
The group cited allegations of beatings, smothering with plastic bags, waterboarding and electric shocks on detainees by authorities.
"Empowered by laws of their own making, Thailand's military rulers have allowed a culture of torture to flourish, where there is no accountability for the perpetrators and no justice for the victims," said Rafendi Djamin, Amnesty International's director for Southeast Asia and the Pacific.
Political rallies and protests are also barred under the junta which has detained scores of people for criticising the regime. Three rights activists behind a landmark report on torture in Thailand's insurgency-hit south are facing jail time for defamation charges filed by the military earlier this year.
"We note that this is taking place in a climate where discussion of torture in Thailand and finding ways to prevent it […] is difficult," Waraich told AFP of the government's move to cancel AI's Wednesday event.
"Torture is taking place, it's taking place by the army, by the police and that's what the report documented," he added.
The government denied accusations of torture, said General Sansern Kaewkamnerd, the spokesperson for the Prime Minister's Office.
"Our investigations into such allegations have shown no indication of torture. I have seen no indication of torture and the Thai people have seen no indication of torture," Sansern told Reuters.