Trump's latest comments indicated he could take a decision before the fortnight deadline he set a day earlier, as he dismissed European efforts to end the conflict and said it would be "very hard" to ask Israel to cease its attacks.

A series of blasts were heard in Tehran on Friday as Israel kept up the massive wave of strikes it says is aimed at stopping Iran from developing nuclear weapons -- an ambition Tehran has denied.

"According to the assessment we hear, we already delayed for at least two or three years the possibility for them to have a nuclear bomb," Israel's foreign minister Gideon Saar said in an interview published Saturday.

Saar said Israel's week-long onslaught will continue. "We will do everything that we can do there in order to remove this threat," he told German newspaper Bild.

As Trump mulls the prospect of joining the war on Israel's side, top diplomats from Britain, France and Germany met their Iranian counterpart Abbas Araghchi in Geneva and urged him to resume talks with the United States that had been derailed by Israel's attacks.

French Foreign Minister Jean-Noel Barrot said "we invited the Iranian minister to consider negotiations with all sides, including the United States, without awaiting the cessation of strikes, which we also hope for."

But Araghchi told NBC News after the meeting that "we're not prepared to negotiate with them (the United States) anymore, as long as the aggression continues."

Trump was dismissive of European efforts, telling reporters, "Iran doesn't want to speak to Europe. They want to speak to us. Europe is not going to be able to help in this."

Trump also said he's unlikely to ask Israel to stop its attacks to get Iran back to the table.

"If somebody's winning, it's a little bit harder to do," he said.

Any US involvement would likely feature powerful bunker-busting bombs that no other country possesses to destroy an underground uranium enrichment facility in Fordo.

On the streets of Tehran, many shops were closed and normally busting markets largely abandoned on Friday.

- 450 missiles -

Since Israel launched its offensive on June 13, targeting nuclear and military sites but also hitting residential areas, Iran has responded with barrages which Israeli authorities say have killed at least 25 people.

A hospital in the Israeli port of Haifa reported 19 injured, including one person in serious condition, after the latest Iranian salvo.

More than 450 missiles have been fired at the country so far, along with about 400 drones, according to Israel's National Public Diplomacy Directorate.

Iran said on Sunday that Israeli strikes had killed at least 224 people, including military commanders, nuclear scientists and civilians. It has not updated the toll since.

A US-based NGO, the Human Rights Activists News Agency, provided a toll on Friday based on its sources and media reports, saying at least 657 people have been killed in Iran, including 263 civilians.

Israel's military said it struck missile launchers in southwestern Iran after overnight air raids on dozens of targets including a nuclear research centre.

In Israel, sirens sounded in the afternoon after missiles were launched from Iran for the second time on Friday. Iran's Revolutionary Guards said they had targeted military sites and air force bases.

Meanwhile, a US Navy official said an aircraft carrier will be moved closer to the Middle East next week, making it the third in or near the region.

- 'Madness' -

"This is a perilous moment, and it is hugely important that we don't see regional escalation of this conflict," said Britain's Foreign Secretary David Lammy, who earlier stated "Iran can never develop or acquire a nuclear weapon."

The International Atomic Energy Agency said that while Iran is the only country without nuclear weapons to enrich uranium to 60 percent, there was no evidence it had all the components to make a functioning nuclear warhead.

"So saying how long it would take for them, it would be pure speculation because we do not know whether there was somebody... secretly pursuing these activities," agency chief Rafael Grossi told CNN.

"We haven't seen that and we have to say it."

Arab League foreign ministers gathered in Istanbul late Friday to discuss the war, Turkish state news agency Anadolu said, on the eve of a weekend gathering of the Organization of Islamic Cooperation (OIC).

Switzerland announced it was temporarily closing its embassy in Tehran, adding that it would continue to fulfil its role representing US interests in Iran.

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