The LÉ Niamh has completed the rescue of 551 people from a wooden barge 55km North of the Libyan coast.
The vessel was tasked this morning by the Italian Marine Rescue Co Ordination Centre (IMRCC) to investigate a sighting of a possible migrant vessel.
Upon arriving on the scene LÉ Niamh came across another vessel with around 700 people onboard.
IMRCC deployed a further four vessels to assist in the operation.
The 551 rescued migrants (384 male, 96 female and 71 children) are now on board LÉ Niamh receiving water, food and medical assistance.
The ship is now en route to Trapani in Italy with and is expected to arrive at 3pm tomorrow.
Earlier, the bodies of around 50 people were found in the hold of a boat off the coast of Libya during a rescue operation, the Italian coastguard said.
A spokeswoman for the Italian coastguard said the Swedish ship Poseidon, working with the European Union's Frontex border control agency, assisted the people on the boat where the bodies were found.
