Australian warship HMAS Darwin has seized more than a tonne of heroin valued at almost $290 million from a smuggling boat off Kenya.

The record 1032-kilogram haul was discovered aboard a dhow in the Indian Ocean, about 27 nautical miles east of Mombasa, Defence says in a statement.

Darwin's crew spotted the vessel on Wednesday and a boarding team discovered 46 sacks of heroin hidden among bags of cement.

HMAS Darwin's Commander Terry Morrison said the seizure removed a major source of funding for terrorist and criminal networks.
"The search tested the steel of Darwin's boarding parties who were working in difficult conditions throughout the night," he said in a statement.

Darwin is taking part in the British-led Combined Task Force 150.

It's one of three multinational task forces conducting security and counter-piracy operations in the Indian Ocean and Persian Gulf region.

Coalition Maritime Force director of operations, Australian captain Craig Powell, said the heroin haul was the largest in the history of the CMF, with a street value of about $289 million.

Australian warships have destroyed large quantities of heroin, hashish and amphetamines during patrols off Africa in the past year.

Drugs are destroyed by dumping them in the sea, and crews of smuggling vessels are sent on their way.

Source: AAP