Anti-government protesters tried to ram their way into Hong Kong's parliament Monday, battling police armed with pepper spray, as the territory marked the anniversary of its handover to China.

The angry scenes ramped up tensions in the international financial hub, which has been shaken by historic demonstrations in the past three weeks -- driven by demands for the withdrawal of a bill that would allow extraditions to the Chinese mainland.

Democracy activists are planning another huge march through the city on Monday afternoon, but small groups of mainly young, masked protesters seized three key thoroughfares in the morning, sparking renewed clashes with police after two weeks of relative calm.

They smashed windows of the city's legislature and tried to force their way into the building by ramming a metal cart through the glass doors.

Riot police inside the building donned gas masks and initially responded from above with pepper spray, but protesters unfurled umbrellas to shield themselves.

Some democratic lawmakers also intervened, pleading with protesters to stop trying to breach the building.

The rallies are the latest reflection of growing fears that China is stamping down on the city's freedoms and culture with the help of the finance hub's pro-Beijing leaders.

Benny, a 20-year-old student who gave only one name, said protesters had been prodded into action by the obduracy of the city's pro-Beijing appointed leadership.

"This isn't what we want, the government forced us to express (our views) this way," he told AFP.

But the increasingly hardline tactics from some protesters have alienated others, with a large counter rally in support of the police taking place on Sunday.

Although Hong Kong returned from British to Chinese rule on July 1, 1997, it is still administered separately under an arrangement known as "one country, two systems".

The city enjoys rights and liberties unseen on the autocratic mainland, but many residents fear Beijing is already reneging on that deal.