Demonstrations against election proceedings in Congo became unruly in two Canadian cities on Tuesday, with at least two arrests in Toronto and officers in Ottawa using tear gas and pepper spray to disperse the protesters.

Two people were arrested during a demonstration by 100 Congolese protesters outside the U.S. Consulate in downtown Toronto. Toronto police said the rally to protest violence in Congo during vote counting for the general election got out of control.

The two arrested were identified as Faki Martin, 26, who was charged with assaulting a peace officer and assault with a weapon, and Bantshi Mbakama, 45, who was charged with attempted forcible entry and two counts of assaulting a peace officer.

Both were also charged with unlawful assembly and are scheduled to appear in a Toronto court Wednesday.

Const. Wendy Drummond told CBC News there were reports of police officers being pelted with dirt, but she could not confirm that.

"They were headed south towards the U.S. consulate when things kind of changed and the crowd there turned against the officers and we had to respond," she said.

Toronto police were forced to call in back-up, she added.

"We had a great response and at this time, all does appear to be in order," Drummond said.

There were no reports of any injuries, she added.

"We do have sufficient units on the scene to deal with the crowds there," Drummond said. "So our job at this time will be to continue to have a peaceful area and to ensure nobody does get injured."

Meanwhile, a protest outside the Congolese embassy in Ottawa also turned violent as protesters threw objects at police. Officers responded with pepper spray and tear gas.

At its height, there were about 300 protesters at the demonstration.

While the initial violence died down, there were sporadic moments of pushing and shoving among participants.

Many of the protesters in Ottawa are supporters of opposition candidate Étienne Tshisekedi and say they are upset over what they are calling the "stolen election" in the Congo.

Kabila ahead in early results

Votes are being counted in Congo's general election, which has been marred by violence and massive logistical problems.

Preliminary results show the country's 40-year-old president Joseph Kabila in the lead.

Congo's 78-year-old opposition leader Etienne Tshisekedi was trailing with 36 per cent of the 12.6 million votes tabulated so far.

Full results were required by law to be released by midnight Tuesday local time, but an election commission spokesperson said they may be delayed.

More than three million people registered to vote in the capital, Kinshasa, and observers say that only two of the four vote tabulation centers there had finished compiling results by Tuesday afternoon.

Even in those two hubs, poll workers had misplaced results from hundreds of polling stations, said observers.

Election violence has already left at least 18 dead and more than 100 wounded, with most of the deaths caused by troops loyal to Kabila, according to a report by Human Rights Watch.

With files from The Canadian Press and The Associated Press