Some 519 migrants were rescued from three separate vessels by the LÉ Eithne in seas northwest of the Libyan capital Tripoli on Monday.
Also on Monday, a Norwegian ship rescued more than 600 migrants from two wooden boats in the southern Mediterranean, the Norwegian police said on Twitter.
The Irish Navy vessel located 104 migrants on an inflatable craft in the early hours of the morning, 50 nautical miles from Tripoli.
Immediately afterwards the craft was called to assist with 362 migrants on a barge in the same area. This operation was completed by 10.16am.
The third rescue from a small fibreglass vessel was completed by 12.40pm.
Of the 519 people rescued, 401 are men, 98 are women and 20 are children.
Excluding the latest rescues, the LÉ Eithne has rescued 1,223 adult males, 248 adult females and 146 minors during its current Mediterranean Sea operation.
The vessel left Naval Service Headquarters in Haulbowline, Cork on May 16th last to assist Italian authorities in search and rescue operations in the region.
A statement said the LÉ Eithne was awaiting direction from the Italian Maritime Rescue Co-Ordination Centre “for next tasking”.
All the migrants picked by the Norwegian ship, the Siem Pilot, were healthy, including several pregnant women, the Norwegian authorities said.
The Siem Pilot is part of the EU’s operation off Italy.
It was originally built to supply oil platforms in the North Sea.
Additional reporting: Reuters