A second Irish Coast Guard search and rescue helicopter has been called in to help in the rescue of a seriously ill woman on board a cruise ship.

The coast guard's newest helicopter, a S92 Sikorsky, was initially sent on the mission.

However, speaking to RTÉ’s News at One, Operations Manager of the Irish Coast Guard Declan Geoghegan said the helicopter encountered some technical difficulties and a second aircraft is now on route.

The initial aircraft stopped on an oil rig to refuel on its way to the MS Marina where it was due to lift an elderly US citizen.

“The aircraft has landed on the rig and has re-fuelled. But we encountered a technical problem”, he said.

“So at the moment we have a following aircraft on the way to assess the situation and we may have to carry out the mission with the following aircraft”, he said.

The crew originally hoped to reach the cruise ship at around 12.30pm.

However, Mr Geoghegan confirmed that they will now wait until the second aircraft, the Waterford Coast Guard Helicopter, arrives at the oil rig before then deciding which aircraft will carry out the rescue mission.

In addition to the coast guard's helicopters, the Air Corps is providing cover to ensure the safety of the search and rescue crew.

A Casa aircraft is helping with communications and also has emergency equipment on board should it be needed for the rescue.

The naval vessel LE Roisin is providing support and monitoring the flight path of the helicopter.