The Canadian Navy has taken control of a cargo ship carrying nearly 500 people thought to be Tamils fleeing Sri Lanka in a bid to enter Canada as refugees.
Authorities are concerned the MV Sun Sea may include people-traffickers and members of the Tamil Tiger rebels, which Canada considers to be a terrorist organisation.
An armed party boarded the ship as it made its way down the coast of Vancouver Island on the Pacific Ocean.
It is believed to have begun its slow trek across the Pacific from Thailand and is reported to have originally been heading for Australia.
Once the passengers and crew come ashore, officials say they will be given medical checks and treated in local hospitals if necessary.
The migrants are then likely to be detained in jails near Vancouver while immigration officers determine who they are.
If confirmed to be carrying Tamil migrants, it would be the second ship in less than a year to reach Canada carrying people from Sri Lanka.
Canadian officials have warned they may take a hard line with the latest arrivals in order to discourage other ships from carrying human cargo.