Treasure hunters who believed they were on the verge of finding Sir Francis Drake’s final resting place have failed to locate his coffin.

The international team last month found two ships which were scuttled off the coast of Panama over 400 years ago.

They believed Drake’s lead-lined coffin could be near to the location of the two wrecks ‘Elizabeth’ and ‘Delight’ and launched a search for the historical artefact.

Pat Croce, who led the underwater expedition, said the mission was unsuccessful – but pledged to return to the site to continue his search.

The 56-year-old, a self-confessed pirate enthusiast and former president of the Philadelphia 76ers basketball team, said: “The expedition was unsuccessful in locating the lead-lined coffin of Sir Francis Drake. But we do have several anomalies or hotspots discovered by the sophisticated remote sensing equipment that coincide with my research. One in particular.”

He said that before he left Portobello, he urged researchers he was travelling with to explore the exact location. They sent a diver down to the 100-foot seabed with a hand-held metal detector to investigate. Mr Croce said: “Unfortunately, the current was so strong that our diver, who was tethered to the survey vessel by an ‘umbilical’ breathing apparatus, considered the conditions too dangerous and he wisely abandoned the search.

“For now, I say to Sir Francis Drake, ‘I’ll be back!’.”

Drake, who was born in Tavistock in 1540, is considered one of Britain’s greatest naval heroes having led the English fleet in victory over the Spanish Armada in 1588 as they prepared for an invasion of Britain.

He was the first Englishman to circumnavigate the globe and the scourge of the Spanish in their ambitions to conquer the world.

Drake was buried in full armour and in a lead lined coffin by his crew.

Mr Croce financed the expedition to the coast off Panama to try to locate Drake’s last known resting place. His 12-strong crew included explorers from Britain, France, Scotland, Australia, Panama and Colombia.

Mr Croce, who runs a pirate museum in St Augustine, Florida, said the ships would remain in the water as they are the property of Panama. He said there was no treasure on board as the ships had been stripped before being scuttled.