Canadian navy personnel recovered 500 kilograms of heroin from a ship in the Indian Ocean in one of the largest drug busts ever on the high seas, the Defence Department announced Sunday.

A dozen crew members from HMCS Toronto, which is patrolling the Indian Ocean as part of an international anti-terrorism mission, boarded what was supposed to be a fishing vessel on Friday.

During a search of the boat, the Canadians found few fish but a good deal of heroin, which has an estimated street value of more than $100 million, according to a Defence Department statement.

The heroin was seized and will be destroyed. No one was injured in the operation.

It is believed that the ship was travelling from Pakistan. However, Conservative MP Chris Alexander, Parliamentary Secretary to Defence Minister Peter MacKay, said Sunday the Canadians were unable to determine the ship’s intended destination.

“Where they were going is almost certainly Africa,” Alexander told CTV News. “But (it was) difficult for them to confirm on the basis of the interviews they did exactly 100 per cent where they were headed.”

Usually, heroin from Afghanistan is shipped to Russia to be exported around the world. But drug cartels, and terror organizations that use drugs to fund their operations, are increasingly turning to maritime shipping routes to get their wares to market.

Commander David Patchell, HMCS Toronto’s commanding officer, called the drug bust “the largest maritime interception of narcotics in the Combined Maritime Forces area of operations and one of the largest heroin seizures in the maritime environment.

"This seizure will have a sweeping impact on these organizations at all levels and demonstrates Canada's commitment to our allies and to ensuring the seas are used for legitimate purposes. It keeps the drugs off the streets and out of the hands of criminals, but it also has a massive impact on the finances of international terrorist organizations."

HMCS Toronto is patrolling the Indian Ocean as part of Combined Task Force 150, an international counter-terrorism operation in the Indian Ocean, the Red Sea and the Gulf of Aden. The frigate set sail in January and is expected to return to Canada this summer.

"This massive narcotics seizure is one example of how our Canadian Armed Forces members deployed in Canada and around the world are making a difference in international security and stability by denying criminals, and possibly terrorists, their source of funding,” MacKay said in a statement.

With a report from CTV’s Richard Madan