Canadian police have arrested two protest leaders in Ottawa and threatened to break up a nearly three-week protest against the country’s Covid-19 restrictions.

Busloads of police arrived near Ottawa’s Parliament Hill, and workers put up extra fences around government buildings. Police also essentially began sealing off much of the downtown area to outsiders to prevent them from coming to the aid of the protesters.

“The action is imminent,” said interim Ottawa Police Chief Steve Bell. “We absolutely are committed to end this unlawful demonstration.”

Police arrested organisers Tamara Lich and Chris Barber around Parliament Hill, but officers were not moving in force on the demonstrators. Police took Mr Lich into custody late Thursday.

Police continued negotiating with the protesters and trying to persuade them to go home, Chief Bell said. “We want this demonstration to end peacefully,” he said, but added: “If they do not peacefully leave, we have plans.”

Many of the truckers in the self-styled Freedom Convoy appeared unmoved by days of warnings from police and the government that they were risking arrest and could see their rigs seized and bank accounts frozen.

“I’m prepared to sit on my ass and watch them hit me with pepper spray,” said one of their leaders, Pat King. As for the trucks parked bumper-to-bumper, he said: “There’s no tow trucks in Canada that will touch them.”

Mr King later told truckers to lock their doors.

Amid the rising tensions, truckers outside Parliament blared their horns in defiance of a court injunction against honking, issued for the benefit of neighbourhood residents.

Ottawa represented the movement’s last stronghold after weeks of demonstrations and blockades that shut down border crossings into the US, inflicted economic damage on both countries and created a political crisis for Prime Minister Justin Trudeau.

The protests have shaken Canada’s reputation for civility and rule-following and inspired similar convoys in France, New Zealand and the Netherlands.

“It’s high time that these illegal and dangerous activities stop,” Mr Trudeau declared in Parliament, not far from where the more than 300 trucks were parked.

“They are a threat to our economy and our relationship with trading partners,” he said. “They are a threat to public safety.”