Police also arrested independence campaigner Andy Chan Ho-tin on Thursday night on suspicion of rioting and assaulting a police officer during a Sheung Shui protest against parallel traders. He was stopped from boarding a plane leaving for Tokyo at Hong Kong airport.

On the June 21 siege of police headquarters in Wan Chai, thousands of demonstrators barricaded entrances and pelted the building with eggs, as they made their demands for a complete withdrawal of the now-shelved extradition bill and an exoneration of those arrested in previous clashes.

Wong and Chow are leaders of the pro-democracy outfit Demosisto, which has been campaigning for democratic self-determination in Hong Kong. Chow was disqualified last year from taking part in a Legislative Council election.

A third member of the party, Ivan Lam Long-yin, was also charged with inciting others to take part in an unauthorised assembly. He was said to be out of town and did not show up at court.

‘I can’t represent 2 million protesters’, Joshua Wong says

In a statement on Friday, Demosisto insisted the recent protests were leaderless and the party was not spearheading them.

“We are very angry about the police creating a chilling effect and white terror through a large-scale arrest of protesters on the eve of August 31,” the party said.

August 31 marks the fifth anniversary of Beijing’s stringent “831 Decision” on Hong Kong’s democratic reforms. Protesters had planned to launch another mass demonstration before they were banned by police.

The party alleged the arrests were politically driven as it involved “movement leaders” which the Chinese Communist Party had named.

“[The arrests] are to paint a picture that the anti-extradition movement was pushed by some masterminds behind the scenes, as to neglect the residents’ five demands,” it said.

A police source said Chow was arrested at her home in Tai Po, while Wong was detained on the street in Ap Lei Chau at about 7am on Friday.

Both were being held for questioning at police headquarters in Wan Chai.

The party’s Facebook page said Wong, 22, was heading to South Horizons MTR station when he was pushed into a private car and taken to police headquarters.

Seen as one of the leaders of the 2014 movement, Wong was jailed in August 2017 for six months for storming the government ­headquarters compound in Admiralty, which sparked the 79-day protest.

A police spokesman confirmed the arrest of a 29-year-old man surnamed Chan on Thursday night at the airport. He was arrested for rioting and assaulting a police officer, the spokesman said.

On Thursday night, Chan wrote on his Facebook page that he was stopped by officers from boarding a plane.

The force told him he was involved in another case handled by the organised crime and triad bureau and that he would be arrested soon, according to Chan’s post.

He had not updated his page since posting the Facebook message shortly before midnight on Thursday.

Chan’s latest arrest came around the time riot officers were clearing protesters on the third night of chaos this week outside Sham Shui Po Police Station.

Earlier this week, police rejected the Civil Human Rights Front’s plan to march from Central to Beijing’s liaison office in Sai Ying Pun on Saturday. The front has been appealing against the ban.

Riot police in Sham Shui Po disperse anti-government protest

Speaking on a radio programme on Friday, front convenor Jimmy Sham Tsz-kit said if they lost their appeal, the march would be postponed.

“The front can only apply for another date for a march. We will not organise an unlawful march,” he said.

The anti-government movement has five main demands, including the bill’s complete withdrawal, the establishment of an independent inquiry into police’s handling of protests and genuine universal suffrage.