Naval helicopters from Helston have helped keep £40 million worth of drugs off the streets after a dramatic seizure involving an overnight chase across hundreds of miles.

Crews of the Normandy Flight, 849 Naval Air Squadron, had only just returned to the Middle East following a period of rest back at home at RNAS Culdrose.

Shortly after their arrival back on foreign waters, however, the Royal Navy support ship RFA Fort Victoria located a suspect dhow as she patrolled the Arabian Sea. This prompted a night and day chase over hundreds of miles of ocean.

At first light, the support ship launched her Sea King helicopters on round-the-clock sorties, tracking the craft across the sea, before guiding a US Navy destroyer into a position to pounce.

Sailors from the USS Laboon boarded the vessel and found 278kg of pure uncut heroin – worth upwards of £40million on the streets of the UK if distributed.

The Sea Kings of Normandy Flight maintained watch of the Americans as they clambered aboard the dhow, photographing and videoing the operation for any future legal proceedings.

Lieutenant Commander Ben Unsworth, Normandy Flight’s commander, said: “This sends a clear message to those wishing to use the high seas for illicit purposes – you can run but you can’t hide. We will find and catch you.”

He said his engineers had worked through the night to ensure the helicopters were ready to launch at dawn and keep an eye on the dhow all day.

“It was immensely satisfying to work with such professional units across several nations to achieve a common aim,” added Lieutenant Commander Unsworth. “It was especially pleasing to get a result so early in the flight’s deployment, setting the bar high for our follow on operations.”

The helicopters – with distinctive black sacks on the side that contain the vital radar – were designed to help protect the Navy from air attack by providing early warning of incoming enemy aircraft. Their radar suite proved so powerful, however, that the Sea King Mk7s are just as much at home over land, tracking moving targets. They were instrumental in helping British forces knock out Iraqi tanks around Basra in 2003 and, during five years in Afghanistan, ensured ground troops seized 40 tonnes of drugs and over 170 tonnes of home-made bombs.

In this mission the two helicopters used their state-of-the-art radar suite to monitor the dhow’s progress, feeding constant reports to Fort Victoria, international Combined Task Force 150, which is directing the counter-terrorism/smuggling mission in the Indian Ocean, and finally the USS Laboon.