Migrants make their way off the MV Sun Sea after it was escorted into CFB Esquimalt in Colwood, B.C. on Friday. Prime Minister Stephen Harper says the federal government "will not hesitate" to change its laws to give authorities greater powers to curb human smuggling in the wake of the arrival of a ship carrying hundreds of Tamil migrants in B.C. last week.

Speaking to reporters on Tuesday in Mississauga, Ont., the prime minister said Canada is a "land of refuge" but the "abnormal" arrival of a ship carrying migrants creates "significant security concerns" the government has a responsibility to handle.

Prime Minister Stephen Harper speaks to reporters during a transit announcement in Mississauga, Ont., on Tuesday. ((Frank Gunn/Canadian Press)) "We will not hesitate to strengthen the laws if we have to, because ultimately as a government, we're responsible," Harper said. "It's a fundamental exercise of sovereignty, and we're responsible for the security of our borders and the ability to welcome people or not welcome people when they come."

The prime minister did not elaborate on what legal changes the government might consider but said the wider issue of human smuggling is a "growing concern" around the world.

"This trend gives us some significant concern, and we'll take whatever steps are necessary going forward," he said.

The MV Sun Sea arrived in B.C. early Friday carrying roughly 490 Tamil migrants, who deny any involvement with terrorism and claim they are fleeing "mass murder" in Sri Lanka. But government officials say they believe there are links between the ship and the Tamil rebel group, the Liberation Tigers of Tamil Eelam, or LTTE.

The group, also known as the Tamil Tigers, has been banned in Canada as a terrorist organization since 2006 for its use of child soldiers and suicide bombers during Sri Lanka's bloody 25-year civil war.

'Lower the tone' on migrant debate: Liberals

Opposition critics have called on the Conservative government to show more compassion for the plight of those on board the MV Sun Sea instead of linking the migrants to terrorism.

Liberal MP Marc Garneau said Public Safety Minister Vic Toews should "lower the tone" of the security concerns and allow the refugee application process to play out. He noted the new cases represented only two per cent of the 30,000 refugee applications Canada receives annually.

"We have an obligation to look at each person in a case-by-case basis," Garneau said. "A sense of proportion would be nice."

As a signatory to the UN Convention on Refugees, Canada is obliged not to send migrants back to their own country if they face persecution there.

But Sri Lankan government officials have chided the Canadian government for not turning away the Sun Sea, saying the money paid to the smugglers by the migrants will go toward the Tamil Tigers' efforts to regroup. Sri Lanka has also denied the migrants' claims that Tamils continue to face abuse and mistreatment in the country following the defeat of Tigers last year.

Immigration officials were expected to begin detention review hearings on Tuesday in Vancouver.

The Canada Border Services Agency reports that of the 492 migrants who arrived aboard the vessel, 63 are women and 49 are children.

Last October, 76 Tamil migrants who arrived in a boat off Vancouver Island claimed refugee status, saying they were fleeing persecution. All were eventually released from custody after allegations that some were linked to the Tamil Tigers were not proven.