The Russian navy has admitted responsibility for a 500-tonne oil spill off the south coast of Ireland this month, an Irish transport ministry spokeswoman said on Thursday.
The accident happened when the aircraft carrier Admiral Kuznetsov was bunkering, or re-fuelling, from a tanker about 50 miles (80 kilometres) southwest of the Fastnet Rock in the Atlantic on February 14.
A high-level Russian military delegation visited Dublin this week and held talks with ministry officials and the coastguard.
"The Russians carried out an internal investigation. They confirmed that a fuel spill had occurred during the bunkering operation and they expressed their regret.
"They were very co-operative and said it was the first time in their naval history that a spill of this size had happened in international waters," the spokeswoman said.
Junior Transport Minister Noel Ahern told parliament that Irish aerial surveillance of the sea at the time of the incident showed the carrier at anchor with an oil tanker alongside.
Two Irish navy vessels and a British warship took samples of the spilled oil for testing by a specialist laboratory in Scotland.
A spokeswoman said initial results showed it was Russian oil.
The spillage created an oil slick of approximately 22 square miles which has since been moving in an easterly direction parallel to the Irish coast.
The spokeswoman said the slick was dispersing at its current location about 40 miles south of Ballycotton in County Cork.
A coastguard-contracted tug was stood down after it used skimmers and other oil recovery equipment with "limited success" due to the dispersed nature of the spill and weather conditions.
"We continue to monitor the slick. It has broken up very significantly but the incident is not closed.
"No oil has made landfall yet. Coastguard officials will be briefed on Friday on how to deal with it if it does come ashore," the spokeswoman said.
