Iran is not currently working on producing a nuclear weapon but could make one within "a year or two" of taking such a decision, Israel's military intelligence chief said on Tuesday.
"The question is not when Iran will acquire the bomb, but how long until the leader decides to begin enriching (uranium) at 90 percent," Brigadier General Aviv Kochavi told parliament's foreign affairs and defence committee in his first briefing since taking up the role in November.
Once such a decision is made, it would take "a year or two" to produce a nuclear warhead, he said, adding that Iran would then need more time to develop an effective missile delivery system for it.
Kochavi said it was unlikely that Iran, which currently enriches uranium to 20 percent, would start enriching it to the 90 percent level needed for a bomb, because it would be in open breach of the nuclear Non-Proliferation Treaty exposing it to harsher sanctions or even a US or Israeli military strike.
He said Iran was reluctant to do this at a time when the country was going through a period of "instability" and "religious tension."
"At the moment, it's not in Iran's interest to move their programme ahead," he told the committee.
Recently, several senior Israeli officials, including the former head of the Mossad overseas intelligence agency, Meir Dagan, have said that Iran is unlikely to acquire nuclear weapons before 2015.
The comments have come amid reports that Israel was involved in a plot to sabotage Iran's nuclear programme through a destructive computer worm called Stuxnet.
Israel, which has the Middle East's sole if undeclared nuclear arsenal, regards Iran as its principal threat, after repeated predictions by its hardline President Mahmoud Ahmadinejad of the Jewish state's demise.
Along with many Western governments, Israel suspects Iran of trying to develop atomic weapons under cover of a civilian nuclear programme -- a charge Tehran denies.
Israel has backed the US policy of leading efforts at the Security Council for tougher UN sanctions against Iran while remaining open to dialogue.
But it has refused to rule out a resort to military action to stop Iran developing a weapons capability.