HMAS Newcastle seizes 581kg of heroin

Australian warship HMAS Newcastle has continued a remarkable spree of mega drug busts, seizing more than half a tonne of heroin from a smuggling dhow off the East African coast.

Based on street values from the UN world drug report for 2014, the 581 kilogram haul was worth $520 million.

That follows a 724 kilogram bust last week, taking Newcastle's total drug haul to 1.3 tonnes, worth more than $1.1 billion.

"We've stopped more than 581 kilograms of narcotics from reaching the streets and the resulting proceeds from feeding back to terrorist organisations," Newcastle's captain Commander Dominic MacNamara said in a defence statement.

Since February last year, Australian ships conducting operations with the Combined Maritime Forces in the Middle East have seized more than four tonnes of heroin.

In a major bust last September, HMAS Toowoomba seized more than five tonnes of hashish from a smuggling vessel off the coast of Somalia.

These drugs mostly originate in Pakistan and Afghanistan and follow ancient ocean smuggling routes to Africa known as the "hash highway" and the "smack track". Seized drugs are dumped back in the ocean while the crews of smuggling vessels are sent on their way.