Israel has closed the country's Mediterranean beaches following reports of oil and other debris washing ashore - probably from an oil tanker leak.
The country's Environmental Protection Ministry issued a warning Monday, advising residents to avoid using beaches near its northern border with Lebanon to the Gaza Strip. Health officials said exposure may cause skin irritations and other illnesses.
The ministry said environment groups, including Israel's EcoOcean nonprofit organization, are conducting a cleanup. Israel's Nature and Parks Authority said spills might affect the area's aquatic ecosystem "for years to come."
Environment groups and volunteers found dozens of marine life including birds, turtles and fish covered in oil.
Ecologists said the spill threatened the population of a reef-building snail called dendropoma petraeum. The snail's already falling numbers could be further affected by the spill.
Israel environment minister Gila Gamliel said it was investigating the spill believed to have originated from a ship passing through the Mediterranean beyond the nation's territorial waters.
European authorities are trying to identify the ship. They say tens or even hundreds of tons of oil was spilled.
The spill may have happened more than a week ago during a storm. Authorities are reviewing hundreds of satellite images.
Through satellite images and weather data, scientists said that they should be able to reverse engineer the spill to pinpoint where it originated.
The environment ministry said at least a dozen possible ships may have been responsible.