The Canadian government, armed with new emergency powers, is promising quick action to clear a three-week old truckers' blockade that has brought the center of the capital Ottawa to a standstill.

Police allowed hundreds of trucks to park in the riverside core of the city and then did little to prevent thousands of largely peaceful protesters taking over Parliament Hill.

Police chief Peter Sloly quit on Tuesday after criticism that he did not do enough to stop protests that began as truckers objecting to cross-border COVID-19 vaccine mandates for rigs but has become more of an anti-government movement also directed at Liberal Prime Minister Justin Trudeau.

Trudeau on Monday invoked the little-used Emergencies Act, allowing the government to boost local police forces.

"That work begins now ... there's an urgency to that response," Emergencies Preparedness Minister Bill Blair said on Tuesday when asked when Ottawa residents could expect order to be restored.

Police say there are 360 vehicles in the city center, down from 4,000 at the peak of the demonstrations. Police have laid 33 charges and made 18 arrests.

Steve Bell, the new acting police chief, told the city council he was confident police had reached the turning point, saying "I believe we now have the resources ... to bring a safe end to this occupation."

One truck driver said the protesters had been taking care of the city.

"When we got here, it was all full of snow. Look who cleaned it up ... There is no garbage," said John, who declined to give his last name. "And we're the terrorists"

Candice Bergen, interim head of the official opposition Conservatives, accused Trudeau in the House of Commons of using an "unprecedented sledgehammer". She noted that a number of truckers' protests at U.S. border crossings had ended.

Trudeau responded that "this is a time for responsible leadership, not crass partisanship" and accused senior Conservative legislators of encouraging the blockade leaders.

(Reporting by David Ljunggren; editing by Grant McCool)