The police presence in downtown Ottawa is growing as efforts to begin clearing a three-week long occupation around Parliament Hill appear imminent but the antigovernment demonstrators aren't buckling.

With rain and sleet falling on the nation's capital, workers began erecting fencing around Parliament Hill and several other buildings downtown, including the Senate, around 8 a.m. Access to the Hill grounds is still open in some places for now.

Larger numbers of police in bright yellow vests are present in the downtown core, most of them moving in groups, handing out more leaflets and warning those present to leave or they could be arrested.

The warnings appeared to be having little effect on people who remained. In one food tent a woman operating two barbecues yelled out the national anthem in French while police stood nearby. 

On Wellington Street as police tried to give leaflets to some demonstrators, they were swarmed and police backed off quickly.

The police are warning with leaflets or verbally that people must leave or they might be arrested and criminally charged. They are also warned their vehicles and other property could be seized, their driver's licence suspended, commercial vehicle registration cancelled, and personal or business bank accounts frozen.

The City of Ottawa is warning them their dogs will be impounded, and the Children's Aid Society of Ottawa Wednesday told parents who have their children with them at the occupation need to make alternate arrangements for their children to be cared for "following potential police action."

The federal government is about to begin debating the use of the Emergencies Act, which Prime Minister Justin Trudeau invoked Monday after more than two weeks of the Ottawa occupation and multiple border crossings blockaded by people making various demands.

Some claim they are there only to end all COVID-19 restrictions, but others, including those who claim to be leading the convoy in Ottawa, have demanded the Liberal government be ousted. They have offered to work with opposition parties to make this happen.

Deputy Ottawa police chief Steve Bell said Wednesday police were ready to use methods people are not used to seeing in the capital and that efforts to clear the streets were imminent.

On Wednesday police handed out leaflets warning of impending arrests and criminal charges against those encamped both downtown and at a parking lot east of downtown that has become a supply yard for those downtown.

The Liberal government has characterized the blockades at the borders and in Ottawa as being connected by a highly co-ordinated, targeted and partly foreign-funded criminal attack on Canadian interests.

They point to the arrest of 13 individuals and seizure of multiple weapons at a convoy in Coutts, Alta., earlier this week, as evidence of a dangerous, criminal element involved. Public Safety Minister Marco Mendicino said Wednesday some of those arrested have ties to people known to be participating in the occupation in Ottawa.

Border blockades in Ontario, Manitoba, Alberta and British Columbia ended earlier this week but police have not moved to clear the Ottawa demonstration until today. The blockade began Jan. 28 and has paralyzed large parts of downtown, with hundreds of trucks and vehicles blocking roads, many of them honking incessantly in what local residents have described as a tortuous. 

Many businesses including the city's largest shopping mall have been closed since the start, and residents and workers say they have been harassed and sometimes physically assaulted for wearing masks in and around the protest.

The Emergencies Act and the enhanced powers are already in effect, including ability to freeze bank accounts of convoy members and ban the presence of public gatherings in specific zones including on Parliament Hill.

However both the House and Senate must confirm the decision to use the act.

The Conservatives and Bloc Québécois say they will not support the motion, but NDP Leader Jagmeet Singh signalled Wednesday his party will hold up the minority Liberals, calling the situation a crisis.

Mia Rabson, Laura Osman and Stephanie Taylor, The Canadian Press