Mossad director's tenure has been extended for another year so that he could prepare for an attack on Iran, Israeli military sources say.

Israeli prime minister Ehud Olmert has decided to keep Meir Dagan behind his desk at Mossad until the end of 2009 so he could take the necessary measures for a possible unilateral military action against Iran, DEBKA website which is close to Israeli intelligence agency quoted the sources as saying.

Israel's intelligence and military brass generally serve for four years, with a traditional one-year extension. Dagan's tenure was last extended by a year in 2007. He is now due to step down in 2009.

The 61-year-old external intelligence chief has played the key role in the main Israeli operations over the past six years, including on a Syrian facility last September, the sources said.

The Mossad chief has his critics at home. In Israel's clandestine agencies, some find his style excessively individualist, secretive and confined to fields which he finds interesting rather than objective initiatives.

Israel, widely believed to be the only possessor of nuclear arsenals in the Middle East, alleges that Iran is trying to develop a military nuclear technology.

Iran, a signatory to the Nuclear Non-Proliferation Treaty (NPT), rejects the allegation as baseless. Tehran maintains it pursues its 'civilian' nuclear activities in the framework of the IAEA regulations to fulfill its growing energy demands.