JERUSALEM: Israeli Defence Minister Ehud Barak flew to Washington on Tuesday for the third time in as many months, as world powers prepared for fresh talks with Iran on its nuclear programme.

"Defence Minister Ehud Barak departed this morning for a working visit to the United States," a statement from his office said. "During the visit Defence Minister Barak will meet his counterpart Secretary of State Leon Panetta and other senior administration officials."

The two last met on April 19 for talks the Pentagon said focused on Iran, Syria and the effects of the Arab Spring on the Middle East.

Israel's Haaretz daily said the latest meeting would, among other issues, finalise an expected US announcement of an extra $680 million (530 million euros) in aid to Israel to help finance the production and deployment of more batteries of its Iron Dome anti-missile system.

Three batteries of the sophisticated system deployed in southern Israel performed successfully during a rocket barrage by Gaza militants in March, and Barak has said he intends to extend it throughout the country.

The system, the first of its kind in the world, was developed by Israel's Rafael Advanced Defense Systems with the help of US funding.

The United States spent $204 million (159 million euros) on the Iron Dome system in 2011.

Israel and the United States say Iran's nuclear energy programme masks a drive to develop nuclear weapons but the two allies disagree on how imminent the threat is. Tehran denies such intentions.

US officials have warned against a potential Israeli pre-emptive strike on Iran, and analysts have predicted Tehran retaliate against Israeli and US targets, with pro-Iranian Hezbollah militants possibly launching rocket attacks on Israel.

Iran and the P5+1 -- Britain, China, France, Russia and the United States plus Germany -- held their first talks in 15 months in Istanbul in mid-April, and agreed to more in-depth discussions in Baghdad on May 23.