The warning, posted online by US embassies in Bahrain, Egypt, Iraq, Israel, Jordan, Kuwait, Lebanon, Oman, Qatar, Saudi Arabia and the United Arab Emirates, came a day after US President Donald Trump threatened to hit Iran "very hard".

Iran and the United States have been at war since February 28. A period of calm followed a ceasefire, though that collapsed with a return of strikes.

With no end in sight, the war has for months upended the lives of people across the Middle East and rattled global energy markets.

"Americans in the region should consider departing, or be prepared to depart should there be escalation," said the security alert.

The messages urged citizens to check flight details and to follow safety advice from local authorities.

"Americans currently in the Middle East should exercise caution and heightened vigilance and should be prepared for flight cancellations, periodic airspace closures, and potential travel disruptions," it said.

US citizens in Jordan were told not to visit military bases in the country, which have recently come under Iranian missile attack, and in Israel they were urged to seek the location of the nearest bomb shelter.

"The Iranian regime is unpredictable, as seen by its recent decisions to attack areas in the region without warning or provocations as well as to expand attacks to areas not previously targeted (such as Egypt)," said a post on the US Embassy Jerusalem site.

The US embassy in Beirut said the mission remained on "ordered departure status", meaning that family members andnon-essential US government personnel were still relocated outside of Lebanon.

Donald Trump said late on Saturday he would hold off on a fresh attack on Iran as long as a deal could be reached quickly to halt Iran's nuclear ambitions and reopen the Strait of Hormuz. 

Iran and "other Middle Eastern Countries" asked for a time to complete a deal that would lead to "the Immediate, Complete and Total" reopening of the Strait and "an end to Iran's nuclear threat," Trump wrote on his Truth Social platform. "Based on this request, I have agreed, for the future benefit of the WORLD and, likewise, the survival of a successful and prosperous Iran, to cancel the attack, subject to being able to rapidly make a DEAL."

Israel "joins me in this commitment," Trump wrote. Israel did not immediately make a public statement on the issue. 

Iran warned the US this weekend against any “adventurous action” and said it would retaliate decisively if American forces followed through on Trump's threats of fresh attacks on Iranian targets.

Iranian Foreign Minister Abbas Araqchi’s comments in separate phone calls on Saturday with senior Turkish, Pakistani and Saudi officials came just hours after Kuwait's army said it destroyed hostile drones launched by Iran against several vital facilities.

Popular

Malaysian pilot risks death penalty for smuggling ecstasy in Indonesia

Social media rumours, economic hardship fuel migrant surge into Ceuta

Mixed-marriage families seek priority in dual citizenship plan