Israel on Wednesday accused Iran of "environmental terrorism" after a devastating oil spill off its Mediterranean coast it said was perpetrated by a Libyan-flagged ship that set sail from Iran.

"A Libyan-flagged pirate ship that departed from Iran was responsible," Israel's environment protection minister Gila Gamliel said on Twitter.

"Iran is waging terrorism by harming the environment," she said, calling the spill "not just an environmental crime but environmental terrorism."

Storms last month washed tonnes of sticky tar ashore along Israel's entire Mediterranean coastline, staining 160 kilometres (96 miles) of beach from its borders with the Gaza Strip to Lebanon.

Gamliel told reporters that the ship responsible had "entered Israel's exclusive economic zone and deliberately polluted" the waters.

The accusation comes after the Jewish state accused Iran of a recent attack late last month on an Israeli-owned ship in the Gulf Oman, further raising tensions between the arch foes.

Iran has denied any role in the explosion that hit the MV Helios Ray, leaving two holes in its side but causing no casualties.

Israel has declared last month's oil spill as one of its worst ecological disasters in recent history.

Volunteers have teamed up with authorities to clean the beaches, while officials from the environmental protection ministry launched an investigation into the source of the spill.

Oil also washed up on southern Lebanon, where thick tar balls hit a swathe of coastline which includes some of the country's best preserved beaches.

The area includes a maritime reserve which hosts a nesting site for turtles which usually appear later in the year.

As well as endangered loggerhead and green sea turtles, the beach provides shelter for the Arabian spiny mouse.

mib/bs/dv