Investigators trying to find the Rescue 116 helicopter managed to get a remotely operated vehicle into the water off the Mayo coast last night.

The Air Accident Investigation Unit (AAIU) confirmed on Monday that they believe the helicopter had struck rocks around Black Rock Island.

The AAIU say they are "anxious" to recover and examine as much wreckage as possible, and to recover the black box flight data recorder.

A significant amount of wreckage has been recovered from the sea and this will undergo detailed examination.

The AAIU say: "This wreckage is primarily from the tail area of the helicopter.

"At this early stage in the investigation it is not possible to be definitive about the exact nature of damage to the recovered wreckage or indeed the circumstances of the accident.

"However, there appears to be marks on some of the recovered wreckage which are consistent with the tail of the aircraft contacting rocky surfaces on the western end of Black Rock.

"The Investigation has not yet definitively identified the initial point of impact."

Equipment aboard search vessels on the surface has detected a signal, which is believed to be from the underwater locator beacon attached to the black box.

This signal points toward an area which will be the focus of further investigation, subject to weather.

Manager of the Irish Coast Guard, Declan Geoghegan, outlines what happened overnight.

"Late last night we go to deploy the ROV just off of Black Rock with the Granuaile and the naval team and the Marine Institute.

"The current was quite strong there and we didn't deploy it for a long period - but it proves that the operation is working.

"We are meeting this morning and then we'll deploy both teams - the naval and the Marine Institute - and Granuaile should be out there in a couple of hours.

"And we'll hopefully have a better result with the weather abating today".