Combined naval forces from Australia and Canada have seized some 500kg of heroin valued at $100 million from a boat in what could be one of global maritime history's biggest multi-national naval operation. The bust operation happened somewhere in the Indian Ocean.

Australia's HMAS Toowoomba, along with Canada's HMCS Toronto warship, tracked and boarded the vessel carrying the heroin last Friday near Tanzania.

Flying an unidentifiable flag, the boat and its haul was believed to be bound for Africa, the Canadian Broadcasting Corp. reported.

"Very quickly on we ascertained they were not being truthful about their mission, their voyage, so we continued on with a full search of the vessel and discovered the drugs," Cmdr. David Patchell of HMCS Toronto said.

Task force commander Commodore Charles McHardie said Australia and Canada had been working together all week to intercept drug trafficking in the Arabian Sea, as he noted that heroin trafficking is considered major funding source for most terrorist groups.

"The destruction of this cargo strikes at the financial heart of global terrorist organisations," Commodore McHardie said.

The task force is one of three commanded by the Combined Maritime Forces (CMF), which involves 27 nations in the naval partnership.

The CMF aims to promote security, stability and prosperity across the Arabian Gulf, the Gulf of Oman, the Red Sea and the Indian Ocean.