Jerusalem — Israel’s prime minister sought to increase pressure on Iran yesterday saying that “all possible means” must be used to stop it acquiring nuclear weapons.

Ehud Olmert’s speech significantly increased the prospect of military action against Iran’s nuclear program.

Israel has twice acted alone to stop regional enemies developing a nuclear capability — in Syria last year and in Iraq during the 1980s.

Mr. Olmert’s speech in America hinted at possible military action against the Islamic republic.

“The Iranian threat must be stopped by all possible means,” he told an audience from the American Israel Public Affairs Committee. “International economic and political sanctions on Iran, as crucial as they may be, are only an initial step and must be dramatically increased.

“The international community has a duty and responsibility to clarify to Iran, through drastic measures, that the repercussions of their continued pursuit of nuclear weapons will be devastating.

“Israel will not tolerate the possibility of a nuclear Iran, and neither should any other country in the free world.”

His words echoed those of President Bush in a speech to the Israeli parliament last month, in which he said: “Permitting the world’s leading sponsor of terror to possess the world’s deadliest weapons would be an unforgivable betrayal for future generations.

“For the sake of peace, the world must not allow Iran to have a nuclear weapon.”

Those Israelis who support military action against Iran feel something must be done before Mr. Bush leaves office next January, as he is perceived to be closer to Israel than any potential successor.

Israel’s neighbor, Syria, was condemned by America yesterday after it refused to open up three military bases suspected of harboring parts related to its clandestine nuclear program.

International weapons inspectors will visit Syria later this month to inspect the al-Kibar facility, which was destroyed in an Israeli air raid last September.

But three other locations identified by American and Israeli intelligence will remain closed to the International Atomic Energy Agency.

The American ambassador to the IAEA, Greg Schulte, said: “It is imperative that Syria fully co-operates with the IAEA.”

America accused Syria of long-term attempts to acquire a nuclear reactor, aided by North Korea.

The Iranian nuclear issue is a much more difficult military problem than that posed by Iraq in the 1980s, when Israel bombed the Osiraq reactor outside Baghdad.

Iran’s nuclear sites are spread over a number of locations, many in mountain bunkers. Israel’s relative distance from Iran means any of its warplanes would be acting at the extreme of their range.

[Israeli prosecutors indicted a former finance minister, Avraham Hirschson, on charges including theft and fraud, Bloomberg News reported yesterday.]