JERUSALEM — Israel's top environmental official on Wednesday accused Iran of deliberately causing the major oil spill that despoiled Israel's Mediterranean coastline last month, an act she described as "environmental terrorism."

Environmental Protection Minister Gila Gamliel said investigators from her ministry had traced the spill, which authorities have described as one of Israel’s worst ecological disasters, to an unregistered Libyan tanker. The ship had called on an Iranian port before approaching the Israeli coast and, turning off its tracking transponder, deposited its cargo of crude oil into the surf, Gamliel said.

“The operator of the ship has black blood on their hands,” she said in a news briefing.

Gamliel, a member of Prime Minister Benjamin Netanyahu’s Likud party, said the findings of the two-week investigation provided strong “circumstantial evidence” that the ship was the source of the leak and its behavior deliberate. She said the government would pursue payment for damages through an international oil pollution compensation program and the ship’s insurance.

But other Israeli government officials, including some in her own ministry, expressed skepticism about her claim, according to local media reports.

Intelligence and naval officials told the Israeli daily Haaretz that their agencies were not involved in the investigation and were unaware that the minister’s accusation was coming.

A military official declined to comment.

The investigation into the oil spill has been underway since mid-February, when massive amounts of sticky black tar appeared along Israel’s 120-mile shoreline. Thousands of volunteers continue to clean the beaches and rocks of up to 1,000 tons of tar. Teams are racing to save turtles, mammals and birds from a sludgy coating.

At least one 55-foot fin whale died of tar poisoning, and health officials slapped a temporary ban on seafood from the area.

The spill also spread north to Lebanon, where the Tyre Coast Nature Reserve serves as an important nesting site for endangered loggerhead and green sea turtles.

Officials said many of the large, visible patches of tar and oil had been scrubbed from the coast. But the complete cleanup was expected to take several months, possibly years. The government has approved an emergency allocation of almost $14 million for the effort.

The spill is believed to have occurred in early February, more than two weeks before the oil was discovered ashore. Investigators, with help from oceanographic agencies in the United States and Europe, have examined imagery of the sea lanes to identify ships in the area, narrowing vessels of interest down to a shortlist.

Inspectors from the Environmental Protection Ministry boarded one of the suspect tankers, the Greek-owned Minerva Helen, at an Athens port Saturday. The next day, after an Israeli court lifted a gag order on the names of the suspected ships, the ministry said the Minerva Helen had been cleared.

Since then, Gamliel said, investigators had identified the Emerald, a Libyan-owned and Panamanian-flagged ship, as the culprit. She described what she characterized as the vessel’s suspicious behavior in early February, re-created by analysts, as it turned its tracking signal on and off while steaming through the Suez Canal and making its way to the Israeli coast.

There, in radio silence, it floated offshore for almost a day, she said, discharging its cargo.

The ship subsequently returned to Iran, Gamliel said. While acknowledging that her investigation hadn’t produced “forensic” proof of Iran’s involvement, she nonetheless directly held Tehran responsible.

“They’re not just hurting Israel,” she said. “Nature and animals don’t just belong to one nation. This is a battle that crosses borders.”