The LÉ James Joyce rescued 423 migrants from 18 separate vessels on Saturday during a search and rescue operation 40 nautical miles northwest of Tripoli, Libya.
In a statement on Saturday afternoon, the Irish Naval Service described the operation as complex.
It started at 8.40am and all 423 people were on board the James Joyce by 1.45pm, where they were given food, water and medical treatment.
In addition to the rescue operation, the Irish naval vessel acted as on-scene coordinator for 5 NGO vessels who rescued an additional 1500 migrants from the 18 vessels.
The LÉ James Joyce is the fifth ship deployed by the Irish Naval Service to the Mediterranean as part of Operation Pontus, which covers humanitarian missions in the region.
It has rescued 1,882 people to date, excluding Saturday’s rescue, since it departed Naval Service headquarters in Haulbowline, Cork On July 8th.
It replaced the LÉ Róisín which had rescued a total of 1,254 people since May 2016.