The coast guard was trying to trace the source of an oil slick yesterday that reached the popular beaches of Vouliagmeni and Varkiza, southern Athens, on Saturday. Beachgoers were swimming in crude oil at midday Saturday after an oil spill brought two slicks – one reaching 30 meters, the other 20 meters – to the coasts of Vouliagmeni and Varkiza, respectively. Sources said the spill was likely caused by a passing vessel but did not rule out the likelihood that it may have come from Lebanon, where the Israeli military shelling destroyed a power plant that spilled massive amounts of oil into the sea. Two coast guard vessels, a contracted private ship and municipal employees joined forces to clean up the area. «At the same time, efforts are continuing from land and sea along the area of Vouliagmeni until Lavrion to determine whether there are anymore oil patches. Up until now no other oil slicks have reached other shores,» the Merchant Marine Ministry said.