HONG KONG – Hong Kong's leader on Tuesday condemned "the extreme use of violence" by masked protesters who stormed and ransacked the city's legislature in an unprecedented challenge to Beijing's authority.

The semi-autonomous financial hub has been thrown into crisis by weeks of massive demonstrations over a push to pass a bill that would allow extraditions to the Chinese mainland.

But on Monday -- the 22nd anniversary of the city's handover to China -- anger spilled over as groups of mostly young, hardline protesters, broke into the legislative council.

Police charged into the building shortly after midnight, firing tear gas and sending plumes of smoke into the air.

In a pre-dawn press conference, Carrie Lam, the city's Beijing-appointed chief executive, described the scenes of vandalism as "heartbreaking and shocking".

"This is something we should seriously condemn because nothing is more important than the rule of law in Hong Kong," she said, with the city's police chief Stephen Lo by her side.

Lo added: "Protesters' violent acts have far exceeded the bottom line of peaceful expressions of demands."

On Monday, some hardline protesters appeared to have reached breaking point, saying they felt compelled to storm parliament because their concerns were going unheard.

The legislature was closed on Tuesday, as police inspected the damage inside the building while workers waited outside to begin a clean-up. – AFP