A ship carrying Sri Lankan migrants is expected to reach B.C.'s shores within the next few days, and preparations to house the estimated 180 people in local prisons are already underway.

An estimated 100 men and 80 women are believed to be onboard the MV Sun Sea, bound from Sri Lanka and carrying the flag of Thailand.

The federal government has expressed concern that the boat could be carrying members of the rebel Tamil Tigers, an organization banned in Canada as a terrorist group.

"Apparently the vessels are connected to a known war-torn area where known terrorists were operating for extensive periods of time," Vancouver immigration lawyer Richard Kurland told CTV News.

"How do you separate wheat from chaff? Often war criminals and terrorists will hide as passengers in a boatload of innocent people. Do you put everyone in detention, just to catch the guilty?"

When the vessel arrives, the would-be refugee claimants will be taken to Maple Ridge, east of Vancouver, where the women will be housed at Alouette Correctional Centre and the men at the Fraser Regional Correctional Centre.

The Fraser prison is where 76 Sri Lankan migrants were held last October when the MV Ocean Lady arrived in Victoria. Those men were detained for three months and released after investigators determined they had no connections to terrorism.

Canada's former high commissioner to Sri Lanka, Martin Collacott, says that he's not surprised another migrant ship has made its way into Canadian water.

"This has been a favourite destination for, particularly, Tamil people," he told CTV News.

"They had a very high success rate in terms of getting into Canada for many years. In one year alone, 2003, we took far more than the rest of the world combined."

In fact, Collacott expects more migrant ships from Sri Lanka to head to B.C. in the future.

He also speculates that the Tamil Tigers' defeat in Sri Lanka after decades of civil war means they're looking to set up support in another country.

"They want to regroup and they want to establish a base, not necessarily a terrorism base, but a fundraising base and a regrouping base, and Canada's the logical place," Collacott said.

The Canadian Tamil Congress believes most of the migrants are fleeing persecution in war-torn Sri Lanka.

"If you are getting raped or you are about to be killed, how can you stay in this country when you are in the face of danger and apply for regular immigration? It's very rough," the group's David Poopalaillai said.

"We are very much concerned about the welfare and wellbeing of the migrants on the ship."

With reports from CTV British Columbia's Bal Brach and Leah Hendry