The story of nearly 500 Tamil migrants who arrived in Canada last week begins decades ago in their home country of Sri Lanka, where separatist Tamil Tiger rebels waged a bloody campaign of terrorism and civil war that lasted for 26 years.

Allegations of abuse and war crimes have tarred both sides of the conflict, and experts say even the end of the civil war last year has failed to calm tensions in the country, particularly for the ethnic Tamils whose lives have been consumed by fighting for a quarter-century.

"The Sri Lankan majority have been in conflict with the Tamil minority for generations; both sides of the fence were guilty of abuses of one kind or another," says former CSIS agent Michel Juneau-Katsuya.

"And now that the Sri Lankan forces have the upper hand, they intend to finish the LTTE (Liberation Tigers of Tamil Eelam) once and for all."

The men, women and children aboard the MV Sun Sea, which arrived in near Victoria last Friday after sailing towards Canada's West Coast for months, are expected to make refugee claims arguing the violence in Sri Lanka makes it too dangerous to return home.

It's a claim thousands of people from the small island country off the southern tip of India have made before, and one that has been successful in an overwhelming majority of cases, making Canada home to the largest Tamil diaspora outside South Asia.

The conflict that has ravaged the northern and eastern regions of Sri Lanka traces its roots to the country's independence from British colonial rule in 1948, a time when the English had favoured the ethnic Tamil minority over the Sinhalese majority.

Independence eventually led to a Sinhalese-led government and policies such as making Sinhala the only official language that minority Tamils saw as oppressive and discriminatory, fuelled an anti-government, separatist movement that eventually gave birth to the Tigers.

In their fight for an independent state called Eelam, the Tigers resorted to assassinations, suicide bombings and the use of child soldiers, often targeting other ethnic Tamils, including Tamil politicians who were sympathetic to the Sri Lankan government.

The group has been labelled a terrorist group in various parts of the world, including Canada, where Ottawa has claimed front groups have used intimidation tactics to extort money from the Tamil diaspora.

Ottawa claims some of the migrants aboard the Sun Sea are themselves members of the Tamil Tigers.

On the other side is a government that itself has been accused of war crimes, especially in the dying days of the conflict, for targeting areas where the Tigers had trapped civilians and for keeping hundreds of thousands of Tamils in government-controlled refugee camps.

By the time the Sri Lankan government crushed the Tigers in May of last year, an estimated 70,000 people had died in 26 years of fighting, and as many as 800,000 people had fled the country. Some of those ended up in refugee camps in neighbouring India, and others sought asylum overseas.

Many of those refugees have found their way to Canada, with Sri Lanka becoming one of the top-10 sources of refugee claimants in this country -- claims that are typically accepted.

Since 2001, more than 13,000 refugee claims involving people from Sri Lanka have been processed, with more than three-quarters of those cases accepted. Compare that to the overall acceptance rate of about 40 per cent of all refugee claims.

And even with the civil war over, the flow of people claiming persecution in back home hasn't abated, as evidenced by the MV Sun Sea and a similar ship that arrived last October carrying 76 refugee claimaints.

An estimated 300,000 civilians were detained in camps for months following the government's defeat of Tamil Tiger rebels in mid 2009, and about 33,000 remain in those camps, although the Sri Lankan government insists they are allowed to freely move out and come back.

Queen's University law professor Sharryn Aiken, an expert on immigration, refugee law and human rights law, says the situation in Sri Lanka is still grim.

"The reality is Sri Lanka is a country with continuing human rights problems that have been well documented," says Aiken.

"The civil war ended, but people are still being persecuted. Basically, we've got a country with an abysmal record on human rights, and no positive signs in terms of lasting peace and reconciliation with its Tamil minority and a lot of people are fleeing the country."

Aiken points to international criticism of Sri Lanka's response to the war crime allegations. It has set up a government-appointed commission that many observers dismiss as a public relations exercise that has largely blocked the involvement of the United Nations.

"The federal government's lack of accountability for war crimes committed particularly at the end of the conflict remains a huge problem," says Aiken.

The Sri Lankan government has lashed out against its critics and points to a UN report from earlier this year that said the end of the civil war means ethnic Tamils from Sri Lanka should no longer be automatic candidates for refugee claims.

The country's high commissioner to Canada, Chitranganee Wagiswara, insists there are no longer compelling reasons to flee Sri Lanka, much less all the way to Canada.

"During the war and soon after the conflict, because of the activities of the Tamil Tiger leaders in Sri Lanka who were holding these people hostage, some of them were in (refugee) camps, but now most of them were out," she says.

"What we say is, why should they come all the way to Canada? If you have a genuine problem, you would go to one of the neighbouring countries."