The Canadian Grand Prix weekend means big business for Montreal's sex trade, as partying race fans roar into the city on their annual pilgrimage.

Experts say major international sporting events, such as the World Cup and the Olympics, raise the demands for young, female prostitutes.

Montreal's annual high-octane extravaganza is no exception, but many of the sex workers who are used to fill the commercial void are unwilling participants, human rights activists say.

Sharon DiFruscia, who's part of a Montreal coalition against human trafficking, said most of the women are exploited as sex slaves.

"Not only in Montreal, but for large sporting events, it's a well-known fact that many women are brought in to the city," said DiFruscia, adding it's difficult to estimate just how many.

"Some of these women are from other countries, but some of them are from our own country."

A Canadian expert on human trafficking says a U.S. report on the global issue released Wednesday shows Canada looks good on paper, but still has a long way to go to stamp it out.

"The bad news is we've not been able to turn our tough talk on human trafficking into action," UBC law professor Benjamin Perrin told The Canadian Press.

"We know that human trafficking is continuing to flourish in Canada and that it's one of the most serious crimes in our country and a fundamental abuse of human rights."

Canada's enforcement slack: report

The annual U.S. State Department report said Canada complies with the "minimum standards," but it also criticizes the country for lacking punch.

"Over the last year, Canada increased victim protection and prevention efforts, but demonstrated limited progress on law-enforcement efforts against trafficking offenders," the document says.

Perrin, who was consulted on the report, said Canada has the basic framework in place to combat human trafficking and protect its victims, but more effort is needed.

He also said Canada has lagged when it comes to rounding up sex tourists, who travel abroad abusing children. Perrin said sex tourism drives human trafficking around the world.

Canada, meanwhile, has convicted only one person in the past decade on sex-tourism charges, he said.

"We've really fallen behind globally in preventing our child-sex offenders from exploiting children in impoverished countries overseas," said Perrin, the founder of The Future Group, a non-governmental organization dedicated to ending human trafficking.

Traffickers rely on student, working visas

The report says most of the women and children exploited in Canada are trafficked primarily from Asia and eastern Europe.

Perrin said many of these foreigners enter Canada on student and working visas or by posing as a relative of someone already in the country.

"It really runs the gamut, there's been no limit to the creativity that traffickers have used to secure the entry of their victims into our country," he said.

He said most trafficked individuals in Canada face psychological and physical threats from their captors. Many don't speak English or French and have been told they will be charged if they go to the authorities.

"It makes human trafficking one of the most under-reported and hard to investigate criminal offences in our entire Criminal Code," Perrin said.

He said a 2004 RCMP estimate states about 600 people are trafficked to Canada for sexual exploitation each year, while another 1,500 to 2,200 are brought through the country on their way to the United States.

Perrin also said major international sporting events, particularly those that draw large amounts of men, have also been a catalyst for human trafficking.

With the Vancouver Olympics in 2010 on the horizon, Perrin is hoping more will be done to minimize the scope of the sex-slave industry.

A 2007 report by The Future Group reported the 2006 World Cup in Germany experienced a short-term increase in the demand for prostitutes, but information campaigns, immigration controls and law-enforcement action likely stopped traffickers from meeting it.

Meanwhile, DiFruscia said demonstrators dressed in black will hand out hundreds of postcards Saturday on Montreal's Crescent Street, the official downtown partying point of the Canadian Grand Prix.

The messages will be addressed to Prime Minister Stephen Harper, demanding he take more action on human trade.

"We're not bashing the Grand Prix; it's just to make sure people are aware when there are big sporting events in a city that this happens," said DiFruscia, the co-ordinator of the social action office of the Catholic Archdiocese of Montreal.