TORONTO, AUG. 11 -- Prime Minister Brian Mulroney reconvened Parliament in an emergency session today to seek sweeping new powers to deal with the influx of refugees into Canada.

Veteran observers in Ottawa said they expected that the House of Commons would approve the government measures by next week. The proposed legislation would sharply raise penalties for ship captains and others who smuggle aliens into Canada and would make it easier for officials to turn away immigrants suspected of being security risks.

Mulroney's decision to interrupt the lawmakers' long summer vacation followed a public outcry against existing liberal immigration policies after a boatload of 174 Indian Sikhs from refugee encampments in Western Europe arrived on the shores of Nova Scotia last month.

An administrative law judge -- called an "adjudicator" here -- yesterday ordered the last six of those Sikhs released from detention at a Halifax military base. The adjudicator denied the Mulroney government's request that five of the men be kept in custody because they were regarded as dangerous.

In Calgary yesterday, another adjudicator allowed six Iranians who arrived in that western Canadian city on Saturday without visas or passports to remain in Canada for at least a month to make their claims for refugee status.

Both groups are among the more than 30,000 persons expected to arrive here this year, without prior authorization, to claim refugee status.

As the United States and governments of Western Europe have cracked down on illegal immigration in recent years, Canada has become something of a haven for migrants and a target for smugglers around the world drawn to the big profits to be made.

Canadian authorities swiftly jailed the 37-year-old Swedish captain who masterminded the scheme to bring the Sikhs to eastern Canada, sentencing him to the maximum one year in jail.

The new powers sought by Mulroney would raise maximum penalties to 10 years in prison and the equivalent of a $375,000 fine. It also would permit the government to detain people until their identity can be established and deport those whose refugee claims are clearly unfounded.

Many immigrants who have arrived recently in Canada dispose of their travel documents before touching Canadian soil. Among bogus refugee claims in the past were those of scores of Portuguese who falsely claimed they were Jehovah's Witnesses and falsely alleged the sect was being persecuted in Portugal.

Church groups, immigration lawyers and opposition critics all acknowledge that there have been abuses, but they contend the government's bill casts too wide a net and that refugees with legitimate claims might also be turned away.