Hong Kong police said they arrested 53 people for illegal assembly after a candlelight vigil attended by tens of thousands of people to mark the 1989 Tiananmen Square crackdown. Police said in a statement that the 53 had marched to another site following the end of the vigil on Saturday and then refused to disperse after midnight. Television news footage showed a tense standoff between a large number of police and around 200 protesters, some of whom were later forcibly removed and carried into police trucks after scuffling with police. \"Police respect the public\'s rights to expression, freedom of speech and assembly but they must follow Hong Kong laws and social order when they express themselves,\" the statement said. Police said some of the 53 were arrested on charges of assaulting or obstructing police. All of those detained were released unconditionally by noon Sunday, a police spokeswoman told AFP. She declined to say whether any political figures were among those arrested. Such arrests are rare in Hong Kong, a former British colony that returned to Chinese rule in 1997 but retains a semi-autonomous status with civil liberties -- including the right to protest -- not enjoyed in mainland China. As many as 150,000 people on Saturday turned up for the annual vigil to commemorate the crushing of student-led democracy protests in Beijing 22 years ago, according to organisers. Police put the crowd figure at 77,000. The sea of people, mostly clad in black as a sign of mourning, held up candles and sang solemn songs, in the only such overt commemoration on Chinese soil. The vigil came as China pursues a roundup of political dissidents, defying world condemnation. It has arrested scores of activists and lawyers since mid-February, including internationally recognised artist Ai Weiwei.China launched its harshest crackdown on dissents in years to prevent the kind of uprisings that spread across the Arab world leading to the toppling of leaders in Tunisia and Egypt.