VANCOUVER -- A petition urging the federal government to change the Immigration Act to fight marriage fraud has been signed by more than 20,000 Canadians.

The Canadian Marriage Fraud Victim Society wants to put an end to the practice of foreigners marrying Canadians as a way to gain permanent residency in the country.

The society is calling for a three-year probationary period, during which couples must live together, before foreign spouses can be granted permanent residency.

"Marriage sponsorship is a very dangerous thing," said society member and abandoned bride Navdeep Dhillon

Many Canadians -- men and women -- who sponsor foreigners are quickly divorced and left financially liable for their ex-spouses under B.C.'s sponsorship default recovery program.

Burnaby resident Shajila Singh escaped her sham marriage, but received a $27,000 bill racked up by her welfare-collecting ex-husband.

Dhillion, 29, paid $1,525 in immigration fees for her ex-husband, who stayed with her for one day in October 2004.

She said she reported her husband to Citizenship and Immigration Canada and was shocked to learn there was no recourse.