The FBI is investigating the public disclosure of a pair of highly classified intelligence documents describing Israel's preparations for a retaliatory strike on Iran, the bureau said on Tuesday.

Multiple news outlets have reported the exposure of highly classified U.S. intelligence material on Israel’s potential plans for a retaliatory attack on Iran.

Iran is Israel's arch-foe and tensions between the two countries are at their highest for years. Israel has pledged to retaliate against an Iranian missile attack on Israel on 1 October. The statement said the group was led by a 23-year-old man,

Israeli police said the security breach was among the most serious ever seen by Israel. "The assessment is that the activity of the members of the ring has caused security damage to the security of the state,

The suspects, all Israeli citizens, conducted intelligence missions for two years under the direction of two Iranian agents, the authorities said.