Fighting broke out between rival politicians in Hong Kong's equivalent of parliament as a debate over extradition laws turned ugly.

Several politicians were seen grappling with each other and one was carried away on a gurney having apparently fainted during the melee.

Others pushed and shoved each other on the floor, as seats seats and tables were sent flying.

The extradition amendments have been widely criticised as eroding the semi-autonomous Chinese territory's judicial independence by making it easier to send criminal suspects to mainland China, where they could face vague national security charges and unfair trials.

Under the "one country, two systems" framework, Hong Kong was guaranteed the right to retain its own social, legal and political systems for 50 years following its handover from British to Chinese rule in 1997.

However, China's ruling Communist Party has been seen as increasingly reneging on that agreement by forcing through unpopular legal changes.

Legislators in the pro-Beijing camp attempted to seat Abraham Razack, also known as Abraham Shek, who had been named earlier in the week through another committee and a contested interpretation of council rules to replace pro-democrat James To Kun-sun as head of the Bills Committee.

However, pro-democracy legislators continued to claim James To is the legitimate chief of the committee guiding discussion of the proposed new law.

Both they and their opponents had scheduled rival meetings on the same topic in the same Legislative Council meeting room on Saturday, starting just 30 minutes apart.

A politician is taken away on a gurney having apparently fainted during the melee. Credit: AP

The two rival committees both claimed to be in charge of the same process of scrutinizing the new law before deciding on whether to vote on it.

At one point, Wu Chi-wai, the Democratic Party chairman who tried to stop Shek from presiding over the meeting, shouted at him, saying "Don't be a sinner for a thousand years! Don't sell out Hong Kong."

Tempers flared and tensions boiled over amid chaotic scenes of jostling, shouting, pushing and shoving, as a media scrum also developed.