Story highlights Wong was reportedly on his way to a speaking engagement when he was stopped in Bangkok

He had been sentenced to community service for 2014 Umbrella Movement activities

Hong Kong (CNN) Joshua Wong, a student leader who helped bring tens of thousands of people onto Hong Kong's streets during pro-democracy protests in 2014, was deported to Hong Kong after being detained at Bangkok airport.

"I was illegally confined and blocked from contacting the outside world by Thai Customs and Police," Wong posted on Facebook

Wong says his passport confiscated soon after arriving in Bangkok on a flight from Hong Kong. Wong was due to take part in a panel discussion organized by student activists to mark the 40th anniversary of Thailand's Thammasart University Massacre.

"After they confiscated my passport, [they] immediately detained me at the airport detention center alone. I'm fortunate to have returned to Hong Kong," Wong said.

"It was a scary 10 plus hours. Sorry for all those who worried about me."