The MV Sun Sea arrived in B.C. in August with 492 Tamil migrants on board. (Department of National Defence)

The arrival in Canada of hundreds of Tamil migrants aboard the MV Sun Sea from Thailand cost the federal government $25 million, according to supplementary budget estimates released by Ottawa.

"This funding will be used to offset expenses incurred to intercept and secure the MV Sun Sea and to process the migrants on board in accordance with Canada's domestic and international obligations," the report said.

The government said the operation cost the Canada Border Services Agency $22 million, the Immigration and Refugee Board $908,000 and the RCMP $2.1 million.

In August, the Sun Sea arrived in B.C. with 492 Tamil migrants on board. As a signatory to the UN Convention on Refugees, Canada must process all refugee claimants who reach Canadian soil.

Representatives of the Tamil migrants said they were fleeing persecution after the country's 26-year civil war between the Sri Lankan government and the Tamil Tigers.

The Tamil Tigers were defeated in May 2009, and a recent UN report states Tamils need no longer be presumed to be fleeing imminent harm in Sri Lanka.

The Canadian government has said it believes suspected Tamil Tigers and human smugglers were hiding among the hundreds of asylum seekers.

Shortly after their arrival, Prime Minister Stephen Harper said that while Canada is a "land of refuge," the "abnormal" arrival of a ship carrying migrants creates "significant security concerns" that the government has a responsibility to handle.

In October, the Conservative government tabled new legislation aimed at punishing anyone who smuggles illegal migrants to Canada.