The HMCS Charlottetown, based in Halifax, Nova Scotia, began trailing the vessel last week because of suspected links to terrorism, Cmdr. Patrick St.-Denis told CTV via phone Thursday.

He said he couldn't discuss the terrorism element, but said sailors spent 17 hours on the ship, whose 11-man Pakistani crew was initially very helpful.

That changed when 170 sacks of hashish weighing 4.3 tons were found in the fuel tanks and under the deck plating, he said.

"They were quite upset that we found something," St.-Denis said.

All of the hashish was dumped into the sea, and St. Denis said the frigate waited until Pakistani maritime security forces arrived before leaving, the report said.