Officials from the UN are leading talks on what international effort is needed to tackle a 140km oil spill along the Lebanese and Syrian coastline.
Fish have been one of the main casualties of the oil spill
Thursday's meeting in Greece aims to draw up a strategy on how to clear up the oil and prevent it spreading.
Representatives from Lebanon, Syria, Greece, Turkey and the EU are expected to attend the talks.
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 has 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 will be hosted by the Greek Maritime Minister Manolis Kefaloyannis, aims to agree on the best way to tackle pollution affecting shorelines in Lebanon and Syria.
The spill was caused by Israeli bombing of the Jiyyeh power station
It will also consider what measures are needed to prevent the slick spreading to neighbouring nations.
The talks will be 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 there were a number of reasons why a concerted effort was needed.
"[We] were conscious to contribute to any effort undertaken to mitigate the impact of the serious pollution incident."
He added that it was important to assist other countries in the region to "take all necessary preparatory measures to face any potential threat of the spill spreading over their waters".
A statement by the IMO said that once a strategy had been agreed, the clean-up and containment operation would begin as soon as possible.