Riot police inside the building donned gas masks and initially responded from above with pepper spray

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.

Protesters 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.

Champagne toasts & flags

Activists have organised a march every handover anniversary, calling for greater democratic freedoms -- such as the right to elect the city's leader.

They have mustered large crowds in recent years -- including a two-month occupation of parts of the city centre in 2014 -- but have failed to win any concessions from Beijing.

This year's rally is framed by unprecedented anti-government protests of the past three weeks that have drawn millions, with the public angry over police using tear gas and rubber bullets to clear crowds.

The spark for the current wave of protests was an attempt by chief executive Carrie Lam to pass the Beijing-backed extradition law, which she has now postponed following the public backlash.

The demonstrations have since morphed into a wider movement against Lam's administration and Beijing.

Lam -- who has kept out of the public eye since her climbdown and has record low approval ratings -- attended a flag-raising ceremony early Monday, marking the moment the city returned to Chinese ownership 22 years ago.

But she and other dignitaries watched from indoors due to "inclement weather" -- the first time in the ceremony's history.

Her speech stuck to the conciliatory tone she has used in recent weeks.

"What happened in recent months has caused conflicts and disputes between the government and residents," Lam said. "It has made me fully understand that as a politician, I need to be aware and accurately grasp the feelings of the people."

She then raised a champagne toast alongside cabinet officials and two of her predecessors.

'Resistance'

During clashes outside the venue at least one woman was seen bleeding from a head wound and officers made multiple arrests.

Some protesters hurled eggs at police, who later said 13 officers were also sent to hospital after being doused by an "unknown liquid".

Activists, who are mainly young students, have vowed to keep up their civil disobedience campaign.

"Whatever happens we won't lose heart," Jason Chan, a 22-year-old accountant added. "Resistance is not a matter of a day or a week, it is long term."

During Sunday's rally, tens of thousands of pro-establishment protesters gathered in support of Hong Kong's police.

Many waved Chinese flags and hurled insults at anti-government demonstrators camped nearby, highlighting the deep ideological fissures now dividing the finance hub.