TORONTO (AP) _ Canada has begun efforts to deport a Dutch immigrant convicted in his native land of collaborating with the Nazis during the German occupation of World War II.

The office of Secretary of State David Crombie said Thursday it has moved to strip Jacob Luitjens, a retired botany teacher at the University of British Columbia, of his Canadian citizenship.

Luitjens, in his late 60s, is fighting the attempt in the federal court. He declined comment to reporters from his home in Vancouver, but five years ago Luitjens denied allegations he helped round up people resisting Nazi rule.

Crombie's spokesman, Jocelyn Francoeur, said full details cannot be disclosed because the case is pending in court.

But Nazi-hunter Sol Littman, Canadian representative of the Simon Wiesenthal Center, hailed the government's action as a breakthrough in catching up with war-crime suspects who entered Canada decades ago.

''We've been after this guy for years and years,'' he said. ''We know the Dutch government wanted him very badly.''

Based on information from witnesses and other sources, Littman alleged that Luitjens and his family belonged to the Dutch National Socialist Party before the war and that Luitjens and his father volunteered for the auxiliary police during the Nazi occupation.

Littman said Luitjens was directly involved in the deaths of a 19-year-old member of the Dutch underground and a German deserter.

He said that after the war Luitjens fled to Paraguay and lived in a Mennonite colony, but was tried in his absence by a Dutch war crimes court in 1948 and convicted of treason.

Treason is not an extraditable offense in Canada. The government rejected previous Dutch requests for Luitjens, who emigrated here in 1961 and retired from teaching four years ago.

The Toronto Star quoted Justice Minister Ray Hnatyshyn as saying that because of the law, deportation, rather than a trial in Canada, ''may be the only option available to us.''

The government set up a war crimes unit in the Justice Department last year, based on the report of a special commission headed by Judge Jules Deschenes.

Unlike the U.S. Office of Special Investigations, Canada chose to concentrate on trying suspects here, rather than deporting or extraditing them as Deschenes also recommended.

The Deschenes report cited 20 cases requiring urgent action and an additional 218 in need of further investigation.

Under Canadian law, citizenship can be revoked if it was obtained fraudulently or by withholding facts that would have disqualified the applicant - such as criminal convictions.

Even if Luitjens loses the citizenship battle, he can appeal deportation through the courts. The law normally requires deportation to the country from which a person arrived, in this case Paraguay rather than the Netherlands.