Former Mossad chief Meir Dagan's declaration that an Israeli attack on Iran would be "stupid" triggered mixed reactions Sunday from senior government and defense officials in Israel.

In his first public appearance since leaving the post in September, Dagan said Friday that the possibility a future Israel Air Force attack on Iranian nuclear facilities was "the stupidest thing I have ever heard".

Two other past Mossad chiefs, Danny Yatom and Ephraim Halevy, said Sunday that Dagan has every right to express his opinion with regard to extraordinary matters such as a strike on Iran.

When it comes to fateful issues pertaining to security and the state, the head of the Mossad must say his piece after leaving the post, Yatom told Israel Radio. Yatom said that he too opposed the idea of attacking Iran as it would not achieve the intended goal.

Halevy echoed this sentiment, saying that an outgoing Mossad chief must grant the public what it is entitled to know, although he added that he might have phrased the declaration differently. Halevy also said that Dagan's remarks should have no bearing on the government's decisions to that regard.

MK Shaul Mofaz, chairman of the Knesset's Foreign Affairs and Defense Committee, agreed that senior defense establishment officials must express their opinions regarding issues such as these whenever possible.

"Dagan's stance is important and he was right to express it, as a man who did an excellent job and contributed so much to Israel," said Mofaz, adding that there was nothing inappropriate about making such a statement at the Hebrew University strategy conference at which he spoke.

Mofaz also said that while Israel could not allow Iran to acquire nuclear weapons, military action must be used only as a last resort.

Other responses were less supportive. Defense Minister Ehud Barak said that while Dagan was a man of many merits who had contributed immeasurably to the security of Israel, he "should not have shared that opinion with the public at large".

Finance Minister Yuval Steinitz agreed, saying he believed Dagan to have been an outstanding Mossad chief but he should have kept the remarks to himself.

In his address to the Hebrew University conference on Friday, Dagan said that Iran has a clandestine nuclear infrastructure which functions alongside its legitimate, civil infrastructure.

It is the legitimate infrastructure, he said, that is under international supervision by the International Atomic Energy Agency (IAEA). Any strike on this legitimate infrastructure would be "patently illegal under international law," according to Dagan.

Dagan emphasized that attacking Iran would be different than Israel's successful air strike on Iraq's nuclear reactor in 1981. Iran has scattered its nuclear facilities in different places around the country, he said, which would make it difficult for Israel to launch an effective attack.

According to Dagan, there is proof that Iran has the capability to divert its nuclear activities from place to place in order to take them out of the watchful eye of international supervision and intelligence agencies. No one in Iran would have any problems in building a centrifuge system in a school basement if they wished to, he said.

The IAF's abilities are not in doubt, Dagan emphasized, but the doubts relate to the possibilities of completing the mission and reaching all targets.

When asked about what would happen in the aftermath of an Israeli attack Dagan said that: "It will be followed by a war with Iran. It is the kind of thing where we know how it starts, but not how it will end."