Tens of thousands of people have gathered in Hong Kong's financial district, with many joining growing crowds after work on Monday. The demonstrators blocked major roads and intersections near the city's government headquarters and in several other areas.

It comes a day after chaotic scenes saw demonstrators fighting hours of running battles with police on Sunday night, choking on clouds of tear gas as officers tried to suppress the crowds.

The pro-democracy protesters have been camped out since late Friday, demanding that Beijing grant genuine democratic reforms to semi-autonomous Hong Kong. They are furious over China's refusal to grant free elections for the city's next leader in 2017.

Although Hong Kong has enjoyed substantial political autonomy since being handed back to China by Britain in 1997, its leader since then has been chosen by a pro-Beijing committee.

It appears the tense scenes of Sunday night have died down somewhat, but many of those who'd gathered on Monday said they were horrified to see police using tear gas on the demonstrators.

"We don't know how the police could do that," teacher Shum Yuen-ping told the AFP news agency.

"We want to have our own democracy, and we came to provide our students with support."

Police have said they used 87 rounds of tear gas on Sunday, in what they described a necessary response to protesters pushing through barricades. Riot police withdrew from the area late on Sunday, but uniformed police remain, manning barricades and blocking access to buildings.

Britain's Foreign Office has voiced concern at the developments, calling on Monday for "constructive talks" that it hoped would eventually lead to a "meaningful advance for democracy."

It said the protesters should exercise their right to demonstrate "within the law," with such rights and freedoms "best guaranteed by the transition to universal suffrage."

The White House urged authorities in Hong Kong to show restraint.

"The United States supports universal suffrage in Hong Kong in accordance with the Basic Law and we support the aspirations of the Hong Kong people," said spokesman Josh Earnest.

Earnest said the position of Hong Kong's chief executive would be given more credibility if citizens could freely choose candidates for the job.

jr/dr (AP, AFP)