Police in Nova Scotia have discovered 83 kilograms of cocaine on a ship that is owned by Prime Minister Paul Martin's sons and named after Martin's wife.

Cape Breton police discovered the drugs bolted to the outside of the Sheila Anne -- a registered Canadian Steam Lines vessel -- during a routine ship examination early Wednesday. Martin transferred ownership of the shipping lines to his three sons last year.

The Sheila Anne had sailed to Sydney from Venezuela. At the time of the search, the ship was carrying a cargo of coal bound for Florida.

The cocaine was found inside an underwater grate at the bottom of the ship, said Martine Malka, a spokeswoman for Canada Steamship Lines.

"This cannot be done through the ship," Malka said. "The only way this could have been done is by divers underwater."

Michel Proulx of the Canada Border Services Agency says the drug seizure is a remarkable find and adds that organized crime groups often exploit legitimate companies to transport illegal goods.

The Sheila Ann and its crew were declared free to leave Sydney late Wednesday.

Canada Steamship Lines is based in Montreal and has offices in Halifax, Winnipeg, Burlington, Ont., Boston, Singapore and Sydney, Australia.

Martin was appointed president of the company in 1974 and took full ownership and control in 1988. He put the company in a blind trust when he entered politics but handed it over to his sons last year amid pressure from opposition parties.