The new scandal builds on an earlier one involving the multibillion-dollar purchase of submarines and missile boats from the same Germany manufacturer.

In November, police recommended charges against four of Netanyahu's confidants, including his cousin and personal lawyer, over corruption in buying the ships. Netanyahu was not named a suspect.

But state prosecutors are said to be considering opening yet another investigation over the latest revelations.

With Gantz's allies in the Blue and White party pummelling the prime minister on television on Saturday night over the new submarine scandal, Netanyahu hastily invited himself into the newsroom of Channel 10, a television station he ordinarily treats as a mortal adversary, for his first interview in several years. He was "on my way to the airport", he said, and thought he "would stop by here and shatter this wave of lies."

He insisted that his investments had been unrelated to his role in buying submarines for Israel, and that he had sold his stock in the company before those deals were made.

"The basic false claim is that I made money on the submarines," he said. "That is a complete lie. I did not make a shekel."

Far from putting the matter to rest, however, the 40-minute television appearance confirmed much of the recent reporting on the submarine scandal and raised troubling new questions.

Netanyahu confirmed that the company on whose shares he had turned a sevenfold profit, clearing more than $US3 million, a year after returning to power as prime minister, was in the supply chain of the German shipyard that builds Israel's submarines. He admitted, after dodging the question for some time, that it was he who had told the Germans that Israel would not object to the sale of advanced submarines to Egypt.

And he acknowledged keeping both Gantz, who was then the army chief of staff, and Moshe Yaalon, then the defence minister, out of the loop about that decision. Yaalon is now the No 2 candidate of the Blue and White party.

"All of Netanyahu's first-time revelations connect to one main suspicion," wrote Amos Harel, the military analyst for Haaretz: "A cloud of conflict of interest hangs over him."

Netanyahu asserted that the decision not to object to the sale of submarines to Egypt was based on "state secrets" that justified his failure to consult either the military chief of staff or the defense minister.

But in Washington on Sunday, Gantz dismissed Netanyahu's state-secrets assertion as ludicrous.

"The sale of submarines, or to give permission to sell submarines to a neighbouring state, this is not a special operation in the middle of the night," he told reporters. "This is going to affect us for many years to come, and it cannot but take place through the formal channels."

"It makes no sense," he added. "Why do we have a National Security Council? Why do we have a Ministry of Defence? Why do we have a Ministry of Foreign Affairs? Why do we have so many official committees, if it comes to one of our most important strategic decisions, and we bypass them all by cousins and lawyers?"

This was not the storyline Netanyahu was aiming for as he headed to Washington. His trip had been carefully orchestrated to remind Israelis, who overwhelmingly admire Trump, of how effectively Netanyahu has managed their relationship. At their meeting, Trump is expected to sign a document formalising the United States' recognition of Israel's sovereignty in the Golan — a strategically important plateau that Israel captured from Syria in the Arab-Israeli War of 1967 but which under international law is considered occupied territory.

New York Times