LONDON, England (CNN) -- Israeli Prime Minister Ehud Olmert said Tuesday that Iran's controversial nuclear program is "a major issue for the entire world" and called for stronger sanctions against Tehran.
Speaking at a press briefing in London alongside British leader Gordon Brown, Olmert stopped short of calling for military action, insisting that economic sanctions are an effective way to deal with Iran's nuclear ambitions.
"Economic sanctions are effective. They have had an important impact already. But they are not sufficient so there should be more. Up to where? Up to the point where (Iran) stops its nuclear program," he said.
The British prime minister echoed Olmert's message, saying that a decision on stepping up sanctions would be made after studying the findings of an International Atomic Energy Association report expected November.
"We have made it absolutely clear that the behavior of Iran is not acceptable. Nobody should be in any doubt as to our resolve on this issue," Brown said.
The United States and some allies accuse Iran of secretly trying to develop nuclear weapons. Tehran, however, insists its program is for peaceful purposes, including generating electricity.
Iran's chief nuclear negotiator, Ali Larijani, resigned recently and was replaced by Saeed Jalili, the deputy foreign minister and a close ally of President Mahmoud Ahmadinejad.
Jalili was set to meet with Javier Solano, the European Union foreign policy chief, on Tuesday in Rome for talks. Olmert said Solano should make it clear to Iran's negotiator the seriousness with which the rest of the world views the situation.
Jalili, however, remained defiant ahead of the talks, insisting Iran planned to "strongly pursue" its nuclear policy.
U.S. President George Bush said recently that "if you're interested in avoiding World War III" it is imperative to stop Iran acquiring the means to make a nuclear weapon.
Over the past week, the Israeli prime minister has been embarked on a diplomatic mission to shore up support for his country's position against Iran.
Olmert made an unscheduled trip to Moscow last Thursday for talks with President Vladimir Putin, after the Russian leader met with Ahmadinejad in Tehran. Olmert said he wanted to make sure that Putin understood the concerns of Israel, which says its security is threatened by Iran's nuclear program. E-mail to a friend