Police in riot gear cleared the main protest hub in downtown Ottawa Saturday, using batons and pepper spray and making dozens of arrests, as they worked to flush out a hard core of demonstrators occupying the Canadian capital.

In a day-long show of force, hundreds of officers pushed into the city center -- facing off in tense scenes with determined protesters who hurled gas canisters and smoke grenades at advancing police, linking arms and chanting "freedom."

An officer smashes a truck window as police deploy to remove protesters on February 19, 2022 in Ottawa, Canada
An officer smashes a truck window as police deploy to remove protesters on February 19, 2022 in Ottawa, Canada AFP / Dave Chan

By the afternoon, police backed by tactical vehicles and overwatched by snipers had cleared Wellington Street in front of the Canadian parliament -- the epicenter of the trucker-led demonstrations that began almost a month ago over Covid-19 health rules.

Trucks were towed and tents, food stands and other structures set up by the demonstrators were torn down.

A line of police push protesters back on February 19, 2022 in Ottawa, Canada
A line of police push protesters back on February 19, 2022 in Ottawa, Canada AFP / Dave Chan

Ottawa interim police chief Steve Bell told a news conference "very important progress" had been made on day two of the operation to clear the protesters, though he cautioned it was "not over."

On side streets around the parliament, a police message boomed by loudspeaker urged die-hard demonstrators, "You must leave, (or) you will be arrested."

Police arrest a demonstrator on February 19, 2022 in Ottawa, Canada
Police arrest a demonstrator on February 19, 2022 in Ottawa, Canada AFP / Dave Chan

A few hundred ignored the order, braving bone-chilling cold into the night while waving Canadian flags, setting off fireworks at a barricade and singing the 1980s rock anthem, "We're Not Gonna Take It."

Bell said 170 people had been arrested since the start of the operation, 47 of them on Saturday.

Demonstrators protest in front of Parliament Hill as police deploy to remove them on February 19, 2022, in Ottawa, Canada
Demonstrators protest in front of Parliament Hill as police deploy to remove them on February 19, 2022, in Ottawa, Canada AFP / ANDREJ IVANOV

He also called out parents for putting their children "at risk" by bringing them "to the front of our police operation."

As tensions ratcheted up, police used what they called a "chemical irritant" -- apparently pepper spray -- against protesters, who they said were being "assaultive and aggressive," launching gas canisters at officers.

Demonstrators pray as as police deploy to remove them on February 19, 2022, in Ottawa, Canada
Demonstrators pray as as police deploy to remove them on February 19, 2022, in Ottawa, Canada AFP / ANDREJ IVANOV

Organizers of the so-called "Freedom Convoy" meanwhile accused police of beating and trampling demonstrators, telling supporters to leave "to avoid further brutality."

Demonstrators pray as as police deploy to remove them on February 19, 2022, in Ottawa, Canada
Demonstrators pray as as police deploy to remove them on February 19, 2022, in Ottawa, Canada AFP / ANDREJ IVANOV

Some truckers had chosen to depart on their own as the police closed in, driving their 18-wheelers away after weeks of demonstrations that at their peak drew 15,000 to the capital.

Protesters lock arms as a police line pushes forward on February 19, 2022 in Ottawa, Canada
Protesters lock arms as a police line pushes forward on February 19, 2022 in Ottawa, Canada AFP / Dave Chan

Others were defiant. "I'm not leaving," said Johnny Rowe at the start of the day.

"There's nothing to go back to," he told AFP. "Everybody here, myself included, has had their lives destroyed by what's happened in the past two years."

"I'm freezing my ass off, but I'm staying," echoed a protester who gave his name only as Brian.

A demonstrator in front of a police line on February 19, 2022 in Ottawa
A demonstrator in front of a police line on February 19, 2022 in Ottawa AFP / ANDREJ IVANOV

An AFP journalist also observed a steady flow of protesters leaving the area.

"We're taking it somewhere else," said musician Nicole Craig, her husband Alex adding: "Even if the truckers have left town, the protest will continue. This fight is not over."

Within minutes of deploying Saturday morning, police had claimed a section of road in front of the prime minister's office.

Officers pointed guns as they smashed truck windows and ordered occupants out, with smoke filling the air.

As the operation unfolded outside parliament, inside the complex, lawmakers resumed debating Prime Minister Justin Trudeau's controversial use of emergency powers -- for the first time in 50 years -- to subdue the protests.

The Ottawa police operation was the largest ever seen in the capital, drawing hundreds of officers from across the nation.

Bell said police had opened several criminal investigations "that relate to the seizure of weapons."

And he warned participants in the protest that authorities -- who've already frozen Can$32 million in donations and bank accounts -- "will actively look to identify you and follow up with financial sanctions and criminal charges."

The Canadian trucker convoy, which inspired copycats in other countries, began as a protest against mandatory Covid-19 vaccines to cross the US border.

Its demands grew, however, to include an end to all pandemic rules and, for many, a wider anti-establishment agenda.

At its peak, the movement also included blockades of US-Canada border crossings, including a key trade route across a bridge between Ontario and Detroit, Michigan -- all of which have since been lifted after costing the economy billions of dollars, according to the government.

Criticized for failing to act decisively on the protests, Trudeau this week invoked the Emergencies Act, which gives the government sweeping powers to deal with a major crisis.

Trudeau has said the act was not being used to call in the military against the protesters and denied restricting freedom of expression.

The objective was simply to "deal with the current threat and to get the situation fully under control," he said. "Illegal blockades and occupations are not peaceful protests."