Hong Kong pro-democracy legislator Nathan Law hit out Monday at "violent attacks" by pro-China protesters at the city's airport on his return from a political forum in Taiwan.

Law, 23, encountered the crowd in the arrivals hall late Sunday.

Protesters, who accuse Law of favouring independence for Hong Kong, shouted, threw liquid in his face and tried to hit him as airport security struggled to bundle him through.

It came after Law and other high-profile Hong Kong pro-democracy activists including Joshua Wong, had been greeted by pro-China protesters in Taipei as they arrived for the forum on Saturday.

The two-day event was an exchange of views between democratic movements in Hong Kong and Taiwan.

"There is never justification for violence, not even in the name of patriotism," Law said in a statement Monday.

"I will continue to fight for democracy and the right of self-determination of Hong Kong people."

At a press conference Monday afternoon he described the attackers as an example of "gangster politics" and accused the Chinese Communist Party of trying to suppress democratic movements.

Fellow pro-democracy lawmaker Eddie Chu, who also travelled to Taiwan, said there was now a "globalised...anti-democratic violent network" controlled by Beijing.

Law and Chu are among a new group of legislators who support the idea of self-determination for semi-autonomous Hong Kong -- a notion that has infuriated Beijing, which resumed sovereignty in 1997.

At one point during Sunday's attack, television footage showed Law stumbling down a staircase after a water bottle was thrown at him.

Protesters shouted: "Trip and die!" and one called Law a "traitor".

Law said he suffered scratches and bruises and had reported the incident to police.

Police said two arrests had been made relating to attacks on journalists covering the incident.

Once a taboo concept, the idea of independence for Hong Kong has gathered momentum since mass protests in 2014 failed to win political reform and as fears have grown that Beijing is tightening its grip on the city.

Two pro-independence lawmakers were last year barred from taking up their seats in the legislature because of irregularities in the way they took the oath of office.

Law and three other pro-democracy lawmakers will face a court hearing in February that will also seek to disqualify them on the same grounds.

They say they are not categorically pro-independence but feel Hong Kongers should have a choice about their future.

The forum in Taipei was hosted by Taiwan's New Power Party, which advocates recognition of Taiwan as a nation.

Even though Taiwan has been self-ruling since the end of a civil war on the mainland in 1949, China still sees it as part of its territory.

Beijing has threatened to take action if Taiwan ever formally declares independence.