Three human rights groups are planning to launch a legal challenge of a proposed immigration bill that would allow the federal government to strip dual nationals convicted of offences such as terrorism of their Canadian citizenship.

Amnesty International, the Canadian Association of Refugee Lawyers and the B.C. Civil Liberties Association are scheduled to announce their plans during a conference call with reporters on Thursday, although the actual lawsuit will have to wait until Bill C-24 becomes law.

The Conservative government's bill would impose new requirements to obtain citizenship and make it easier for the government to revoke it.

Under the proposed law, dual citizens who are convicted of treason, terrorism or espionage could lose their citizenship. The law could apply in cases in which those citizens are convicted in foreign courts, and it could also apply to people born in Canada if they also have citizenship elsewhere, such as through their parents.

Minister of Citizenship and Immigration Chris Alexander responds to a question during question period in the House of Commons on Parliament Hill. (Sean Kilpatrick/CP))

Currently, someone may be stripped of Canadian citizenship for attaining it through false representations.

The advocacy groups behind the forthcoming lawsuit argue the proposed law is unconstitutional. They say giving the government the power to revoke people's citizenship is the same as banishing them into exile.

"In Amnesty International's view, the proposed new revocation provisions are divisive and buy into and promote false and xenophobic narratives about 'true' Canadians and others, which equate foreignness with terrorism," says a report released last week by Amnesty International Canada.

The groups argue the current bill, which allows the government to rely on convictions in foreign countries, does not include enough safeguards to protect Canadians.

Opposition MPs and other advocacy groups, including the Canadian Bar Association, have also objected to the bill.

Immigration Minister Chris Alexander has fiercely defended the proposed law, insisting Canadians support the idea of stripping citizenship from people convicted of war crimes or terrorism.

"Under the new act, we would have the power to revoke it when someone has refused to reveal that they committed crimes, that they committed human rights abuses, that they committed war crimes," Alexander told Parliament last week.

"And yes, Canadians find it entirely acceptable that we should revoke the citizenship of dual nationals for terrorism, spying or treason."