The US has urged its nationals to immediately leave most of the Middle East due to "serious safety risks", as the US-Israeli war against Iran widens.

On Monday, the US State Department said Americans should "depart now via commercial means" from Bahrain, Egypt, Iran, Iraq, Israel, the occupied West Bank and Gaza, Jordan, Kuwait, Lebanon, Oman, Qatar, Saudi Arabia, Syria, United Arab Emirates and Yemen.

Washington has so far not organised any evacuations in the region, where many flights have been cancelled or suspended since the US and Israel began striking Iran on Saturday.

Iran responded by firing missiles and drones at Middle Eastern nations allied to the US.

Between 500,000 and one million US nationals are estimated to be living in the Middle East.

Exact official numbers are not available as Americans are not required to register with US authorities when they move abroad.

American citizens were urged to check "the latest security updates" with nearby embassies and consulates, and given hotlines for if they need help leaving the region.

The US embassy in Jerusalem said on Monday that it "is not in a position at this time to evacuate or directly assist Americans in departing Israel", adding that it would be closed on Tuesday.

It later said Israel had "begun operating shuttles to the Taba Border Crossing [with Egypt]" but warned that the embassy "cannot make any recommendation (for or against)" using it.

On Tuesday, France said it was ready to fly back those of its citizens who were most at risk in the Middle East.

French Foreign Minister Jean-Noël Barrot told the country's BFM TV broadcaster this could be done using both commercial and military flights.

About 400,000 French nationals are thought to be in the Middle East.

On Monday, UK Prime Minister Sir Keir Starmer urged all British citizens in the region to register their presence so the government could provide "the best possible support".

Foreign Secretary Yvette Cooper told the BBC there were an estimated 300,000 British citizens in the region.

She said many of those trapped were holidaymakers, passengers transiting through the Gulf or people on business visits.

The UK government has previously used registration schemes to provide urgent updates to people affected by international crises - but the number of people and countries affected in this case is unprecedented.