Hong Kong democracy activist Joshua Wong said Sunday he had been arrested for breaching bail conditions on returning home from a trip to Taiwan.
Wong, 22, was among multiple prominent democracy advocates who were detained late last month in a roundup by police as the city reels from more than three months of unprecedented pro-democracy protests.
He was accused of "inciting others to take part in unauthorised assembly" among other charges and later released on bail.
Last week Wong travelled to Taiwan where he met with local politicians and gave speeches about Hong Kong's fight for democracy.
He said he was arrested on his return on Sunday morning.
"I was arrested by police for 'breaching bail conditions' this morning at the airport's customs and I am detained in custody now," he said in a statement released by his political party Demosisto.
The statement suggested Wong believed a procedural mistake had been made because the court had previously approved overseas trips.
"It is expected that I will be released after a hearing tomorrow morning so I hope fellow friends don't worry too much," he said in the statement.
Hong Kong police did not respond to a request for comment.
The city's crisis-hit government has largely refused to back down over the protests, which have seen millions march, closed the airport and left city streets strewn with bricks and shrouded in tear gas.
What started as a pushback against a bill allowing extraditions to mainland China quickly morphed into wider calls for democracy and police accountability.
Last week city leader Carrie Lam made a surprise u-turn and scrapped the extradition law but protesters have said that gesture was too little, too late.
Among the current goals of the movement are an amnesty for the more than 1,100 people arrested so far, an independent inquiry into the police and universal suffrage, all demands that have been rejected by Lam and Beijing.
Wong began his career as an activist when he was just 12-years-old and later became the poster child of the huge pro-democracy "Umbrella Movement" protests of 2014 that failed to win any concessions.
He has previously been jailed for his involvement in those protests.