A massive oil slick moving towards Ireland and the UK is more than three times larger than originally estimated, the Irish Government warned today.
The spill, discovered close to where a Russian warship was refuelling in the Celtic Sea, is now believed to be 1000 tonnes - revised upwards from 300 tonnes - and could reach Irish and Welsh shores in just over two weeks.
The incident has sparked a flurry of diplomatic contact between Ireland and Russia, while British authorities have also been drawn into the ongoing investigations.
A Russian destroyer, a British destroyer, an Irish Naval vessel and a Russian aircraft carrier are all at the scene of the spill about 50 miles south of Fastnet, off the west Cork coast, along with an ocean-going tug and two refuelling tankers.
The Irish government has asked the Russian embassy in Dublin to hand over samples of the oils carried onboard the Russian tankers and aircraft carrier.
While some of the slick - originally covering an area of around 2.8 miles by 3.1 miles - will break up or evaporate, the bulk of it is expected to remain on the surface, and is veering eastwards at around 12 miles a day.
"The residual oil remaining is expected to develop into tar balls," said a spokeswoman for Ireland's Department of Transport.
"Depending on weather conditions these may end up on the Irish south east coast in approximately 16 days time and also impact on the Welsh coastline.
"At this point it is too early to predict accurate volumes."
Both the Irish Coast Guard and the UK Coastguard are carrying out aerial surveillance flights, using special sonar equipment, over the area today while a tug is being launched from Cork to carry out tests to see if the oil is recoverable at sea.
But authorities believe from past international experience that it is too difficult to contain and capture such a slick before it reaches shorelines.
Friends of the Earth, the environmental organisation, has described it as a "significant spill" bound to cause serious damage to marine life and has called for a full investigation.
Samples of the oil have been taken from the scene for analysis, while Government departments and agencies are being constantly briefed about the potential impact to the environment.
Irish authorities were alerted to the spill on Saturday through a satellite surveillance pollution report by the European Maritime Safety Agency in Lisbon.
The Russian Navy confirmed one its carriers was refuelling at sea from a Russian supply tanker and said it was carrying out its own internal investigation.