THE largest ever cocaine haul seized by the Royal Navy was hailed today as a "massive blow to the narcotics industry".

Commander Andrew Stacey revealed details of the five and a half tonne drugs stash with a street value of £240 million.

It was recovered when the crew of HMS Iron Duke spent more than 24 hours scouring a drug smugglers' boat off the coast of South America, eventually smashing through a concrete floor and unbolting steel panels.

Cdr Stacey said: "This was our third successful drug bust in as many months but this surpasses anything we've had and anything the Navy had previously.

"It is the largest drugs bust by value and by volume in terms of cocaine.It is a massive blow for the narcotics industry.

"My team are delighted and all our hard training and preparations have paid off."

The crew swooped on September 15 off the coast of South America with the US coast guard and another British ship RFA Fort George.

HMS Iron Duke sent an armed helicopter and rigid inflatable boats to stop the 138-foot fishing boat MV Cristal. After a fastidious search 212 bales of cocaine were found, weighing about 26kg each.

The drugs were hidden under the ship's regular stores.

Tonnes of stock had to be moved, the hard floor broken up with sledge hammers and metal panels unbolted before the stash was revealed.

Minister for the Armed Forces Bill Rammell said: "Again, the Royal Navy has successfully damaged the trade in this vile substance, which only serves to poison our communities.

"The crew rightly deserve our praise and thanks for the work they do on our behalf."

Prince William served on HMS Iron Duke last year and was involved in an operation which saw it seize cocaine worth £45 million in the Caribbean.