TORONTO -- The Canadian government dispatched a flotilla of Coast Guard vessels, Navy warships and planes to search Atlantic coastal waters last weekend for a fishing boat that was rumored to be bringing in more illegal immigrants.

But embarrassed officials called off the three-day operation after they learned that the aged herring boat being sought was anchored off the coast of Devon, England, without passengers or cargo.

Opposition critics accused the government of staging a diversion to mask a failed refugee policy. But Immigration Minister Benoit Bouchard told reporters that given another chance, with the same information, he would do the same thing.

Canadians are jittery about illegal aliens after the arrival of thousands by plane, bus and vessel in recent months. Long-building resentments flared after a boat brought 174 Indian Sikh migrants to the shore of Nova Scotia last month. Bouchard said his department had received thousands of telephone calls from angry people, 99 percent of whom, he said, have demanded, 'Send them back.' "

At the request of Prime Minister Brian Mulroney's government, House of Commons Speaker John Fraser yesterday recalled members of Parliament from vacation to consider measures to toughen Canada's liberal refugee policies and make it more difficult for those who come in illegally to stay. Parliament will reconvene Tuesday.

About 17,000 aliens claiming they were escaping political persecution at home arrived in the first half of this year. Immigration officials said they believe that two-thirds of these claims are bogus. Nevertheless, few aliens who reach Canada are deported.

Migrants can work or draw welfare and enjoy almost all the rights of Canadian citizens while they wait up to five years for their claims to be processed by a cumbersome bureaucracy. If an alien marries a Canadian citizen or establishes himself as a solid citizen, he is allowed to stay for "humanitarian" reasons.

Canada received an award from the United Nations last year for its acceptance of refugees. But the generous policies have also been a lure to non-refugees seeking a better standard of living and to smugglers eager to serve them, for a price. Canada has also become a haven for refugees who are caught in immigration crackdowns in Europe and the United States.

Salvadorans and Guatemalans who had been living illegally in the United States began streaming into Canada by bus late last year after a new U.S. immigration law was passed. The Sikhs who landed in Nova Scotia, like a boatload of Sri Lankan Tamils who came to Newfoundland last August, had been living in West Germany and elsewhere in Europe -- where aliens often are prohibited from working and are restricted in their movements.

Royal Canadian Mounted Police aided by Canadian Air Force spotter planes found their ship off the coast two days after the Sikhs landed in Nova Scotia. Police apprehended the ship's Swedish captain, Rolf Nygren, and members of the crew.

The captain pleaded guilty to violating Canada's immigration laws for allowing the Sikhs to disembark his ship. He was sentenced to one year in prison and fined the equivalent of $3,750. Crew members were also jailed or fined. All but six of the aliens were allowed to settle in Toronto and Vancouver while their appeals for political asylum are heard.

Canadian officials said they believe the swift punishment of the captain and crew will deter others.

Last year, officials imposed a visa requirement on persons coming from Turkey and Portugal. Scores of the Portuguese said they were Jehovah's Witnesses and were fleeing Portugal because they were being persecuted by the Catholic Church. When Canadian officials investigated, they determined that there was no such persecution and that most of the immigrants were unknown to the Jehovah's Witnesses in Portugal.

The number of Brazilians, Sri Lankans and Iranians seeking asylum also has risen. While attention was directed at the seacoast last week, a Sri Lankan couple and an Iranian man seeking refugee status arrived at an island in the Canadian Arctic on a flight from Greenland. The Sri Lankans said they had traveled from Sri Lanka to Pakistan to Moscow to Helsinki to Greenland.

Leaders of Canadian Sikh organizations argued that the public outcry over the Sikh refugees revealed an undercurrent of racism against Asians. Most of those who object on radio call-in shows and in bars say they they think it is unfair for illegal entrants to be allowed to settle here while others going through authorized channels have to wait years in their countries to get visas to come here legally.

Many express concern about terrorism. Indian diplomats in Canada say there are now more members of radical Sikh organizations in Canada than in India.

Extremist Sikh groups have been the focus of a long investigation into the 1985 bombing of an Air India flight bound from Toronto to Bombay. Four Sikhs were given prison sentences in Vancouver recently for trying to assassinate a Punjabi Cabinet minister when he visited the city last year.

Two Sikhs were sentenced to life imprisonment in Montreal for plotting to blow up another Air India jet. Last month, a Sikh priest in Toronto was charged with attempted murder after stabbing a man during a religious dispute.

Even Canadians who talk tough about limiting immigration generally unbend when they are exposed to the people behind the statistics.

In a poll taken by the Toronto-based Environics survey organization last fall, 70 percent of those questioned said Canada is accepting too many immigrants. But, said Environics pollster Donna Dasko, "when we ask specific questions, like should we allow immigrants who have family members here, the answer is usually yes, and when we ask if we should exclude racial minorities the answer is no."

Academicians and Canadian businessmen argue that Canada should open the doors wider for immigration. With birthrates down to about 1.67 percent and emigration to the United States by native Canadians, they say, present levels of immigration are too low. Canadian officials say they expect about 30,000 alleged refugees this year and about 115,000 migrants.

"Economically, immigrants are a bargain," wrote Morton Weinfeld, chairman of the sociology department at Montreal's McGill University, in the Toronto Globe and Mail last month. "Children of immigrants are rapidly taking their place among the best and the brightest in Canadian schools and universities. The work ethic is alive and well among newcomers."