Hong Kong protesters plan to block one of the world's busiest airports on Saturday after a night of violence in which police used tear gas and rubber bullets to break up crowds, the latest clashes in 14 weeks of unrest in the Chinese-ruled city.

Hundreds of demonstrators, many masked and dressed in black, attacked metro stations on Kowloon peninsula on Friday night, targeted because of televised scenes of police beating protesters on a metro train on Aug. 31 as they cowered on the floor.

Activists tore down signs, broke turnstiles, set fires on the street and daubed graffiti on the walls on Friday.

"The behaviour was outrageous," the government said in a statement.

Hong Kong leader Carrie Lam announced concessions this week to try to end the protests, including formally scrapping a hugely unpopular extradition bill, but many said they were too little, too late.

The bill would have allowed extraditions to mainland China, despite Hong Kong having an independent judiciary dating back to British colonial rule.

But the demonstrations, which began in June, have long since broadened into calls for more democracy and many protesters have pledged to fight on.

Demonstrations have at times paralyzed parts of the region, a major Asian financial hub, amid running street battles between protesters and police who have responded with tear gas, pepper spray and water cannon. Violent arrests of protesters have drawn international attention.

Saturday's planned demonstrations include yet another "stress test" of the airport aiming to disrupt transport links to Chek Lap Kok, built in the dying days of British rule on reclaimed land around a tiny island of the same name and reached by a series of gleaming bridges.

An anti-extradition bill protester walks near a burning barricade in Hong Kong on Friday. (Tyrone Siu/Reuters)

The airport announced that only passengers with tickets would be allowed to use the express train service on Saturday, boarding in downtown Hong Kong. The train would not stop en route, on the Kowloon peninsula. Bus services could also be hit, it said.

The measures are aimed at avoiding the chaos of last weekend, when protesters blocked airport approach roads, threw debris on the train track and trashed the subway station in nearby Tung Chung in running clashes with police.

Protesters also occupied the arrival hall last month, halting and delaying flights, amid a series of clashes with police.

Hong Kong returned to China in 1997 under the "one country, two systems" formula that guarantees freedoms not enjoyed on the mainland. Many Hong Kong residents fear Beijing is eroding that autonomy.

China denies the accusation of meddling and says Hong Kong is its internal affair. It has denounced the protests, warning of the damage to the economy and the possible use of force to quell the unrest.

In addition to calling for a withdrawal of the extradition bill and the release of those arrested for violence, protesters want an independent inquiry into perceived police brutality, retraction of the word "riot" to describe rallies and the right for Hong Kong people to choose their own leaders.

The protests have presented Chinese President Xi Jinping with his greatest popular challenge since he came to power in 2012.