LONDON - When the crew of a Royal Navy helicopter spotted the Cristal off South America, their suspicions were aroused as the rusty trawler, with no nets in sight, ploughed through an area notorious for drug traffickers.

Within hours, HMS Iron Duke had made the largest haul of cocaine in British naval history.

Interception of the 42m boat off Brazil on September 15 led to the discovery of more than 5 tonnes of the narcotic, with a street value of £240 million (NZ$530 million).

The previous largest haul was 4.7 tonnes of cocaine, discovered in 1999. Hidden beneath tonnes of fishing supplies and a false concrete deck in the hold, which had to be broken by sledge hammers, were bales of drugs.

British sailors and the United States Coastguard took 24 hours to search the vessel.

The Cristal's crew were arrested and handed over to the Coastguard with the drugs.

- INDEPENDENT