Israeli Prime Minister Benjamin Netanyahu said on Monday it was time to ramp up sanctions against Iran to try to curb its nuclear programme after discussing the matter with visiting Russian President Vladimir Putin.

In his first public comments on the inconclusive round of talks in Moscow last week between world powers and Iran, Netanyahu repeated Israel's three core demands.

"I believe two things must be done now: strengthening the sanctions and also boosting the demands," Netanyahu said, without mentioning the possibility of Israeli military action should diplomacy fail.

The international community must call for the cessation of all uranium enrichment in Iran, the removal of all enriched uranium from the country and the dismantling of the Furdow underground nuclear facility, he added.

At the Moscow talks, Russia, the United States, China, Britain, France and Germany set no date for further political negotiations.

Last month, and again in the Russian capital, world powers asked Iran to close the Furdow facility where uranium is being enriched to 20-percent fissile purity, and to ship any stocks out of the country, demands that come close to those of Israel.

Israel wants all Iranian uranium enrichment to stop, but is uneasy about the West's current focus on halting only higher-percentage enrichment close to a level needed to produce material for nuclear bombs.

European governments on Monday formally approved an embargo on Iranian oil to start on July 1. Debt-ridden Greece had pushed for a delay because it relies heavily on Iranian crude to meet its energy needs, but EU governments said the embargo would go ahead as planned.

"We had an opportunity to discuss the negotiations under way between the international community and Iran," Netanyahu said of his meeting with Putin.

"We agree that nuclear weapons in the hands of Iran represents a grave danger, first of all to Israel, but also to the region and to the entire world," he said.

Putin, in his own comments to reporters at Netanyahu's residence, said they discussed Iran's nuclear programme and the situation in Syria "in great detail". He did not elaborate.

Russia takes a softer tack than the Western nations and opposes any further sanctions against Iran. Putin has said Russia has no proof that Tehran, which denies it is seeking atomic weapons, intends to become a nuclear-armed power.

His trip to Israel, the Palestinian Territories and Jordan is seen as an effort to increase Russia's clout in the region at a time when the West and some Arab nations have criticised Moscow for opposing their efforts to force out Syrian President Bashar al-Assad.

The visit, officially billed as an opportunity to dedicate a memorial in central Israel to the Red Army's battles against Nazi Germany in World War Two, began a day after the Muslim Brotherhood's Mohamed Mursi was declared the winner of Egypt's presidential election.

The outcome of the poll in Egypt, which signed a peace treaty with Israel in 1979, has raised concerns in Israel.

On Syria, Russia has brushed aside U.S. and Arab calls to stop sending weapons to the government there, saying it supplies only defensive arms. It has also used its veto power in the United Nations Security Council to protect Syria.

Assad has helped Russia keep a foothold in the Middle East by buying billions of dollars worth of weapons and hosting a maintenance facility for the Russian navy, its only permanent warm-water port outside the former Soviet Union.