Joshua Wong, the student activist who became a global symbol of the fight for democracy in Hong Kong, has reportedly been detained in Thailand following a request from China and will shortly be flown back to Hong Kong. Wong's political party Demosist? posted on Facebook that he had travelled to Bangkok after being invited to speak at the city's Chulalongkorn University about his campaign for democracy. However Netiwit Chotipatpaisal, the Thai student-activist who was due to meet Wong in Bangkok, notified the party that Wong has been detained at Suvarnabhumi airport. "According to Chotipatpaisal, the Thai authorities have received a letter from the Chinese government earlier regarding Wong's visit. His request to see Wong, who is still currently in custody, has also been declined," the Demosist? post said. "Demosist? strongly condemns the Thai government for unreasonably limiting Wong's freedom and right to entry, and requests the immediate release of Wong. "In the meantime, we request the Hong Kong immigration department's assistance in assuring Wong's safety." The Guardian understands that Wong will return to Hong Kong on Wednesday. One source with knowledge of the trip said he was currently being held in custody at the airport. Immigration officials at Suvarnabhumi Airport confirmed to Reuters that Wong was prevented from entering Thailand and would be sent back to Hong Kong. Prominent members of Hong Kong's pro-democracy movement accused Beijing of being behind Wong's deportation. Agnes Chow, the deputy secretary general of Demosist?, said: "We believe that the Chinese government is using all ways to stop us spreading democratic ideas from Hong Kong to other countries. But bigger suppression makes a stronger fight. "We just hope that Joshua is safe," the 19-year-old activist added. "We will not give up the fight for democracy and the fight against the Chinese government which disrespects human rights." Nathan Law, Demosist?'s president, told Hong Kong radio he believed there was "some connection" between Wong's detention and Beijing. Wong, 19, was due to address students at Chulalongkorn University at an event to mark the 40th anniversary of a massacre of pro-democracy students by security forces and royalist militias in 1976. The Thammasat massacre of 6 October 6 1976, remains a deeply sensitive issue in Thailand's turbulent recent history, and was the prelude to a military coup. He was expected to talk about his experiences during the 79-day umbrella movement protests in Hong Kong in 2014. Jason Ng, a Hong Kong-based writer who knows Wong, said that before leaving Hong Kong the student activist had voiced concerns that he might not be allowed to enter Thailand. The suspected abduction of Hong Kong bookseller Gui Minhai last year by Chinese agents had also left Wong nervous about potential risks to his well-being. "He was... most concerned about his personal safety, being abducted or attacked. Being turned back is one thing, getting hurt or disappearing is another," said Ng, the author of a book on Hong Kong's umbrella movement protests. To guard against such threats, ahead of Wong's trip to Thailand supporters set up an encrypted group on the messaging service WhatsApp through which the activist could notify Bangkok-based academics and journalists of any problems. Wong's detention appeared to be the latest example of the closer ties between Thailand's military regime and China's Communist rulers, who consider the student activist a subversive. Since the 2014 coup in Thailand, a series of incidents have underlined Beijing's influence in the south-east Asian country. In October last year a Hong Kong publisher who specialised in salacious books about the Communist party elite vanished from his seafront apartment in the Thai resort town Pattaya, only to reappear in custody in mainland China where he is now being held. At around the same time, a Chinese journalist and campaigner called Li Xin fled China, hoping to claim political asylum in Thailand. However, he disappeared while traveling from Thailand to Laos. "I warned him to be very careful in Thailand. It is very dangerous here," one Chinese exile living in Bangkok said at the time. A number of other Chinese dissidents and members of the Uighur ethnic minority from western China have also been deported back to China at the request of its government. Netiwit, who said he waited at the airport until 3am after Wong's Emirates Airline flight landed at 11:45pm, said his treatment amounted to "censorship". "Actually Joshua Wong was just in Taipei, Taiwan, and he was able to travel there and stayed there for two-to-three days," he told the Khaosod news website. "Thailand should stay out of the Chinese sphere of power, but we're not able to do this." Sophie Richardson, China director at Human Rights Watch, said: "Thailand's arrest of Joshua Wong, a well-known pro-democracy activist in Hong Kong, sadly suggests that Bangkok is willing to do Beijing's bidding. Wong should be freed immediately and allowed to travel and exercise his right to free expression."