UN officials have drawn up an action plan to tackle a huge oil spill along the Lebanese and Syrian coastline.
Experts estimate that the initial clear-up will cost 50m euros (£34m), with more funds required next year.
The plan calls for immediate aerial surveys to assess the extent of the damage and a workforce of 300 people to tackle the worst-affected sites.
The measures were agreed at a meeting in Greece attended by Lebanon, Syria, Greece, Turkey and the EU.
The executive director of the environment programme at the United Nations, Achim Steiner, said it was a sad fact that the environment was a victim of the conflict.
"Now the bombs have stopped and the guns have been silenced we have a chance to rapidly assess the true magnitude of the problem and finally mobilise the support for an oil clean-up and a restoration of the coastline," he said in a statement.
"The experts are on standby and today the international community have agreed on an action plan.
"I sincerely hope we have secured the financial backing to swiftly and comprehensively deliver on this promise to the Lebanese people, on this request to the UN for assistance from the Lebanese authorities."
Up to 15,000 tonnes of oil poured into the Mediterranean Sea last month after Israeli forces bombed a power station.
Marine experts were unable to visit the worst affected areas while the conflict between Israel and Hezbollah continued, but Monday's ceasefire allowed them to begin on-the-ground assessments.
Local environmental and conservation groups said that some of the oil had settled on the sea floor, threatening areas where tuna spawn.
They also voiced concern that slicks on beaches would prevent young green turtles, an endangered species, from reaching the sea after they had hatched.
The meeting in Piraeus, which was hosted by the Greek Maritime Minister Manolis Kefaloyannis, agreed on measures to tackle pollution affecting shorelines in Lebanon and Syria.
Testing of oil samples to see if they contain persistent organic pollutants, which are a potential risk to human health
Protection of sensitive areas such as nesting sites for birds and turtles, World Heritage Sites and tourist locations
The talks were co-chaired by UN Environment Programme (Unep) executive director Achim Steiner and Efthimios Mitropoulos, secretary general of the International Maritime Organization (IMO).
Mr Mitropoulos said the action plan set the stage for wide-ranging assistance needed by the Lebanese and Syrian authorities.
"I sincerely hope that the damage to the environment is contained to the current level and that other Mediterranean Sea countries do not suffer as a result of the oil spill, also that we can all learn a lot from this tragic incident and take these lessons forward so we are better prepared in the future," he said.
Computer models suggest that about 20% of the oil has probably evaporated, with almost 80% now on the coastline, and around 0.25%, or some 40 tonnes, remaining at sea.
However, satellite images suggest that far larger amounts may remain afloat, with the potential to spread much further a field.