By Steve Scherer

OTTAWA (Reuters) - Canadian police on Sunday are making possibly the final push to clear the capital city of demonstrators who have paralyzed it by parking and camping on the streets for more than three weeks to protest against pandemic restrictions.

Police have made 170 arrests and towed 53 vehicles since they began efforts to bust up the protest on Friday morning that required Prime Minister Justin Trudeau to invoke rarely used emergency powers.

On Saturday, police used pepper spray and stun grenades to move out the die-hard protesters who have remained, clearing most of the area in front of parliament and next to the prime minister's office.

But pockets of entrenched protesters still remain. Some of those arrested on Saturday wore body armor and had smoke grenades and other fireworks in their bags and vehicles, police said.

"This operation is still moving forward. It is not over and it will take more time until we have achieved our goals," Ottawa's Interim Police Chief Steve Bell said on Saturday.

The protesters initially wanted an end to cross-border COVID-19 vaccine mandates for truck drivers, but the blockade turned into a demonstration against Trudeau and the government.

Trudeau on Monday invoked emergency powers to give his government wider authority to stop the protests, including sweeping powers to freeze the accounts of those suspected of supporting the blockades, without obtaining a court order.

"Police are making their way through the streets methodically and responsibly. This is encouraging, but the work is not yet done," Public Safety Minister Marco Mendicino said on Saturday.

Protesters, who have been filmed by police, will be held accountable, Bell said.

"We will actively look to identify you and follow up with financial sanctions and criminal charges. ... This investigation will go on for months to come."

(Reporting by Steve Scherer; Editing by Richard Chang)