Hong Kong democracy activist Joshua Wong has been detained on arrival at Suvarnabhumi airport.
Wong, 19, famed for his galvanising role in the city's 2014 pro-democracy umbrella movement, was held as he landed at the airport late Tuesday, his party Demosisto said in a statement, citing a Thai student activist, Netiwit Chotipatpaisal, who was due to meet him.
Wong was invited by Thai student activists to take part at an event marking the anniversary of a military crackdown in October 1976.
Demosisto strongly condemns the Thai government for unreasonably limiting Wong's freedom and right to entry, and requests the immediate release of Wong, the statement said.
Joshua Wong, 19, was detained by immigration officials upon his arrival to Suvarnabhumi Airport late Tuesday night at Beijing's request, according to Netiwit, a Thai student activist who had invited him to speak at Chulalongkorn University.
According to Khaosod, Netiwit said he waited at the airport until 3am after Wong's Emirates Airline flight landed at 11:45pm.
Netiwit said it was the tourist police at the airport which told them Wong had been detained at China's request.
He said actually Joshua Wong was just in Taipei, Taiwan, and he was able to travel there and stayed there for two-to-three days. Thailand should stay out of the Chinese sphere of power, but it was not able to do this.
However as of 7am, Netiwit said none of his contacts in Hong Kong had confirmed Wong had returned there, and he was concerned about where Wong was being held or taken.
Wong was to participate in the only semi-official, semi-public discussion of the 1976 massacre on Thursday evening at Chulalongkorn University.
In 2014, Wong shot to fame after leading the so-called Umbrella Revolution's massive, peaceful street protests calling for direct elections.
Source: Thai Public Broadcasting Service (Thai PBS)