The arrest followed the latest protests on Wednesday in which police fired water cannon and tear gas and arrested more than 300 people as demonstrators defied the sweeping security legislation introduced by China to snuff out dissent.

There were no signs of protests on Thursday.

Police posted pictures on Twitter from Wednesday's disturbances showing on officer with a bleeding arm saying he was stabbed by "rioters holding sharp objects". The suspects fled while bystanders offered no help, the police said.

A police spokesman said the arrested man was surnamed Wong but could not confirm whether he was leaving Hong Kong or working at the airport.

Media, citing unidentified sources, said the suspect was on board a Cathay Pacific flight to London due to depart just before midnight. A witness said three police vehicles drove towards a gate as a Cathay Pacific plane was preparing to take off and about 10 riot police ran up the bridge to the aircraft.

The suspect held an expired British National Overseas passport, a special status which provides a route to citizenship, the source told the Cable TV station.

Former Hong Kong leader Leung Chun-ying posted on Facebook on Wednesday that a bounty of $HK500,000 ($A93,360) would be offered to anyone helping catch the fugitive.

China's parliament adopted the security law in response to protests last year triggered by fears Beijing was stifling the city's freedoms and threatening its judicial independence, guaranteed by a "one country, two systems" formula agreed when it returned to Chinese rule in 1997.

Beijing denies the accusation.

Hong Kong and Beijing officials have said the law is vital to plug holes in national security defences exposed by the protests, pointing to the city's failure to pass such laws by itself as required under its mini-constitution, the Basic Law.

Another unfulfilled constitutional requirement for Hong Kong is to introduce universal suffrage, the protesters' main demand.

The new law punishes crimes of secession, subversion, terrorism and collusion with foreign forces with up to life in prison. It will also see mainland security agencies in Hong Kong for the first time and allows extradition to the mainland for trial in courts controlled by the Communist Party.

Ten of the arrests made on Wednesday involved violations of the new law, police said, with most of the 360 or so others involved illegal assembly and other offences.

In the latest diplomatic tension over the law, China said Britain would bear all consequences for any offer to Hong Kong citizens of a path to settlement.

China also denounced the United States after the US House of Representatives passed legislation that would penalise banks doing business with Chinese officials who implement the national security law in Hong Kong.

Democratically ruled and Chinese-claimed Taiwan advised its citizens to avoid unnecessary visits to or transit through Hong Kong, Macau or mainland China. Britain and Canada have also updated their travel advisories for Hong Kong, warning their citizens of detention risks.

Australian Associated Press