Scores of divers have joined in renewed efforts to find the bodies of two winchmen from an Irish Coast Guard helicopter which crashed into the Atlantic last month.

Rescue 116 crashed off Co Mayo at 12.46am on March 14 with four crew on board after it struck Blackrock island 12 miles offshore.

Air accident investigators have found that one of the Sikorksy S-92's internal warning systems did not include the rocky outcrop's terrain or its working lighthouse in its database.

The wreck of the helicopter was discovered on the seabed just off the island.

Captain Dara Fitzpatrick, commander of the flight, was pulled from the sea hours after the crash while the body of his co-pilot, Captain Mark Duffy, was taken from the cockpit 12 days later by divers at depths of 40 metres.

The bodies of winchmen Paul Ormsby and Ciaran Smith have not been found in spite of weeks of intensive surface, shore and seabed searches.

Divers from clubs affiliated with the Irish Underwater Council joined the Garda sub-aqua unit and local fishing boats for focused inspection of the seabed around Blackrock.

The renewed seabed searches began after Blackrock island was scaled by mountaineers from the Irish Army and Garda crime scene examiners last week.