Hong Kong police fired tear gas at protesters on Monday as a general strike plunged the Asian financial hub into fresh chaos, paralyzing transport and bringing the city to an unprecedented standstill for much of the morning.

As some train and bus services resumed, tens of thousands of demonstrators fanned out across several districts, where protests again degenerated into running clashes with riot police.

Speaking to the media for the first time in two weeks, Beijing-backed leader Carrie Lam warned again that the protests were pushing the city to the edge of an "extremely dangerous situation" and represented a challenge to China's sovereignty.

Lam remained defiant as she rejected calls from protesters demanding her resignation, saying the government would be resolute in maintaining law and order.

She warned that the protests were putting the former British colony on a path of no return and had hurt its economy.

"They claim they want a revolution and to restore Hong Kong. These actions have far exceeded their original political demands," said a stern-faced Lam, flanked by senior members of her administration.

"These illegal acts that challenge our country's sovereignty, and jeopardize 'one country two systems', will destroy the stability and prosperity of Hong Kong," she said, referring to the territory's administrative system since 1997, when it was handed back to China.

Lam warned that the protests were pushing "the city we all love and many of us helped to build, to the verge of a very dangerous situation".

The protests pose the greatest political challenge to the government of the former British colony since it returned to Chinese rule and represent the biggest popular challenge to Chinese leader Xi Jinping since he came to power in 2012.

Some demonstrators accused Lam of again fueling the crisis by ignoring public sentiment, however, and pledged to continue their movement.

It was "totally a waste of time" to hear her speak, said Jay Leung, 20, a university student.

"I don't think the government is doing anything to heal society," he added. "They provide no solution to solve the political problem brought on by themselves."

Russell, 38, who works in the tourism industry said, "Nothing, she said nothing. I didn't hear anything positive, she just made it worse."