Israel closed all its Mediterranean beaches until further notice after an offshore oil spill deposited tonnes of tar across more than 160 kilometres of coastline in what officials are calling one of the country's worst ecological disasters. Activists began reporting globs of black tar on Israel's coast last week after a heavy storm. The deposits have wreaked havoc on wildlife, including a young fin whale washed up on a beach in southern Israel that died after ingesting the viscous black liquid. The Nature and Parks Authority called the spill “one of the most serious ecological disasters” in Israel’s history. In 2014, a crude oil spill in the Arava Desert caused extensive damage to one of the country's delicate ecosystems. The Environmental Protection Ministry and activists estimate that at least 1,000 tonnes of tar, the product of an oil spill from a ship in the eastern Mediterranean earlier this month, have already washed up onshore. The ministry said the incident was being investigated. Yoav Ratner, co-ordinator of the ministry's oil spill contingency plan, said there were still many “unknown unknowns” about the extent of the ecological damage, so it was difficult to say how long clean-up would take. Thousands of volunteers took to the beaches on Saturday to help clean up the tar, and several were admitted to hospital after they inhaled toxic fumes. The military also sent out thousands of soldiers to assist in the operation. The Environmental Protection, Health and Interior Ministries issued a joint statement on Sunday warning the public to stay away from the country's 195km Mediterranean coastline, cautioning that “exposure to tar can be harmful to public health”. Environmental Protection Minister Gila Gamliel told Hebrew media that her department estimates the clean-up project will cost millions of dollars. Prime Minister Benjamin Netanyahu toured one of the tar-pocked beaches on Sunday and praised the ministry’s work. Representatives from a coalition of Israeli environmental groups said in a press conference on Sunday that the ministry was woefully underfunded and that existing legislation did little to prevent or address environmental disasters. Arik Rosenblum, director of the Israeli environmental group EcoOcean, said the Environmental Protection Ministry was “fighting this situation and many other situations with their hands tied behind their back” because of inadequate legislation.