Duncan Campbell in Vancouver, guardian.co.uk, Tuesday 7 September 2010 16.58 BST

The arrival off the west coast of Canada of a rusty boat containing nearly 500 exhausted Sri Lankan Tamil asylum seekers has sparked an angry debate about racism that has divided national opinion. The merchant vessel Sun Sea limped, under escort, into Esquimalt naval base in British Columbia on 13 August after a four month voyage from Songkhla in Thailand. The passengers spoke of grim conditions. One man died during the journey and was buried at sea. “It is a miracle that they survived,” David Poopalapillai of the Canadian Tamil Congress (CTC) told the Guardian. “The boat is very primitive, you wouldn’t even go out fishing in it.” He ascribed their survival to the fact that they had been living for many months in very hostile conditions in Sri Lanka.

The 380 men and 63 women are being held in detention centres near Vancouver. The 49 children on board are with their mothers although not officially detained. Hearings into whether the Tamils can be released while applications for refugee status are processed are due to start tomorrow .

Even before the boat reached Canada, it had stirred up controversy. The Conservative prime minister, Stephen Harper, described the vessel as “abnormal”, claimed that it created security concerns and warned that he could seek a change in the law to deal with similar arrivals. Canada’s public safety minister, Vic Toews, said that it could contain members of the Tamil Tigers and that it was a “test ship … part of a broader organised criminal enterprise”.

The government has been accused of scaremongering by the opposition, immigration lawyers and refugee groups. The Liberal party leader, Michael Ignatieff, criticised suggestions that the boat should have been turned away, as happened to similar vessels approaching Australia. He said during a recent political rally in Winnipeg: “This is Canada, not Australia. That means Canada has principles, the charter of rights and freedoms, our international obligations.”

Canada has a long history of welcoming refugees, from 200,000 Hungarians who fled after the failed 1956 uprising to more than 100,000 US draft resisters who crossed into Canada during the Vietnam war. There were also darker times; coincidentally, last week, details were announced of a monument to commemorate the St Louis, a ship carrying Jewish refugees from Nazi Germany in 1939 which was turned away by the Canadian government. Many of its 900 passengers subsequently died in concentration camps.

Lorne Waldman, the lawyer representing more than 50 of the asylum seekers, told the Guardian that before the boat landed the tone was set. “From the get-go, it was suggested that there were criminals and terrorists aboard,” he said. “The Sri Lankan government has a huge interest in portraying them this way rather than as victims of a genocidal civil war. Some of those on board are victims of torture and have shrapnel wounds.”

Waldman, who represented a smaller number of Tamils who arrived last October on another boat, the Ocean Lady, said that terrorist claims had been made then but none substantiated.

Professor Rohan Gunaratna, who is advising the Canadian government, said, in an email from his home in Singapore, that the Tamil Tigers had “decided to regroup in Canada where (they) have traditionally raised funds and lobbied politicians that depended on the migrant-diaspora vote.” He claimed there was evidence that the Tamil Tigers had organised the voyage.

An opinion poll last month indicated that a majority of Canadians wanted the Tamils to be sent back.

“Why such rage directed at such a minuscule group?” asked columnist Stephen Hume in the Vancouver Sun. “Perhaps it’s because they aren’t white … How we respond to a few Tamils seeking safety and a future for their children says far more about us than it does about them. And what it says so far is rather distasteful.”

This provoked a furious reaction. “Gee, could it be that we are sick of being played for Patsies?” was one of the milder responses from readers. “You might sing a different song if your community was flooded with Hindus, Vietnamese, etc who brought such worthy skills with them as drive-by shootings, drug wars, murder of their own wives and daughters,” read another.

Poopalapillai, of the CTC, which represents about 200,000 Tamils, mainly in the Toronto area, blamed the Sri Lankan government for raising the spectre of terrorism. “If there are any undesirable residents, put them through due process,” he said. “Most of these folks went through persecution and hostile conditions. The only thing they had in their mind was to save their lives.” Of the opinion poll, he said: “Canada is a very compassionate country but people were not very well informed at the time this poll was taken.”

A government spokeswoman said that the average process time for refugee status was 21 months but the hearings this week could lead to the conditional release of at least some of the asylum seekers once their identities had been established.