Mossad chief Tamir Pardo flew to the US capital to consult with his American counterparts amid speculation over a possible Israeli strike against Iranian nuclear facilities, CIA director David Petraeus and Senator Dianne Feinstein revealed at a congressional hearing.

Sensitive trips by intelligence chiefs are usually kept secret but Feinstein, the chairwoman of the Senate Select Committee on Intelligence, mentioned Pardo's visit at a televised hearing as she discussed how Israel views Iran's nuclear ambitions.

"Well, the vice chairman and I have just met this past week with the director of Mossad, so that is a classified meeting," Feinstein said at the hearing.

The Central Intelligence Agency director confirmed the meeting and said he was frequently talking to Israel's leaders, who he said viewed Iran's nuclear program as an "existential threat."

"Like you, obviously, I met with the head of Mossad when he was here," Petraeus said.

"That is part of an ongoing dialogue that has also included conversations that I've had with Prime Minister (Benjamin) Netanyahu and with (Defense) Minister (Ehud) Barak -- the latter almost on a monthly basis in the nearly five months that I've been in the job," he said.

Feinstein cited her meeting with the Mossad director after asking US intelligence chiefs about the likelihood of possible pre-emptive military action by Israel against Iran's nuclear sites.

US National Intelligence Director James Clapper replied that sanctions would hopefully convince Tehran to abandon its nuclear work but said he would prefer to answer the question in a closed-door session.

Israeli officials have sent conflicting messages about potential military strikes on Iran.

President Shimon Peres on Tuesday reaffirmed that "no option should be excluded against the program of Iran, which seeks to acquire weapons of mass destruction."

"The regime of the ayatollahs is the most corrupt in the world, from a moral point of view," Peres told a conference in Herzliya, near Tel Aviv.

The United States and other Western governments accuse Iran of seeking an atomic weapons capability, something Tehran has always denied.

Israeli leaders fear a nuclear-armed Iran would pose an existential threat to the Jewish state, which has the Middle East's sole if undeclared nuclear arsenal.

Some Israeli media reported in October last year that the option of pre-emptive air strikes on Iran was opposed by the country's intelligence services but favored by Netanyahu and Barak.

Maj. Gen. Paolo Serra was handed control Saturday of the U.N. Interim Force in Lebanon -- UNIFIL -- taking over from Maj. Gen. Alberto Asarta Cuevas of Spain.

Serra takes over after Italy moved to reduce its troop contingent from 1,800 to 1,100 soldiers following attacks on peacekeepers in May and July -- a move Rome said was made not in response to the attacks but as part of a wider round of defense cuts.

Serra was handed command of UNIFIL at its headquarters at Naqoura, Lebanon, in a ceremony attended by the Lebanese Defense Minister Fayez Ghosn, Lebanese armed forces commander Gen. Jean Kahwagi and Italian Defense Minister Giampaolo Di Paola, among other dignitaries.

Serra said he is "fully committed" to working with the Lebanese armed forces to train them to take over security at the border between Israel and Lebanon and promised to further develop the strategic partnership with them.

He said peace and security for the region "lies in the continued commitment of all the parties to the cessation of hostilities and full respect of (U.N.) Resolution 1701," which was enacted to resolve the 2006 Israel-Lebanon conflict.

Part of the resolution calls for the two sides to adhere to the Blue Line, which marks the border between the countries.

"The respect for the Blue Line by the parties and their cooperation in UNIFIL's efforts to further the visible marking of the Blue Line is a process that can support the improving of the general security for the people of southern Lebanon," Serra said.

Di Paola told the Beirut newspaper The Daily Star Italy remains firmly committed to UNIFIL despite the troop cutbacks and last year's attacks on peacekeepers.

Five Italian troops were wounded in an attack on a UNIFIL convoy in May, followed a month later by a roadside bomb attack on French troops in which five were also wounded.

Another attack in December near Tyre wounded a further five French peacekeepers and one Lebanese civilian.

Di Paola noted the violence of the incidents, but added, "overall, the incidents do not change the situation," on the ground.

"When you look to the role of UNIFIL, and what they have been able to achieve, together with the Lebanese army, (it is hard to deny) the fact, we are contributing to bringing stability … in a very sensitive area."

Di Paola noted the "Italian contribution is one of the strongest," and added, "I am quite convinced and quite confident about the level of contribution."

Also present in Lebanon was Italian Secretary of State for Foreign Affairs Staffan de Mistura, who told The Daily Star, "Lebanon is part of the Mediterranean and is a priority country for Italy."

He said the importance of UNIFIL was evident in that "11 months after the outbreak of the crisis in Syria, and except for some small incidents, the crisis has not affected Lebanon."