US embassies in several Middle Eastern capitals warned American citizens to beware an “unforeseen escalation” in the regional conflict and urged them to be ready to leave.

“Americans in the region should consider departing, or be prepared to depart should there be escalation,” said a security alert, versions of which were posted on social media by the US missions in Amman, Jerusalem, Muscat, Baghdad and Beirut.

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.

Americans in Jordan were told not to visit US military bases there, 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 that the mission remained on “ordered departure status,” meaning that non-emergency US government personnel were still relocated outside of Lebanon.

On Wednesday, a drone struck a US-owned gas vessel moored in an Egyptian port, causing a fire. Egypt is investigating but has not yet accused any group of launching the attack.

Iran’s military, meanwhile, has accused Washington of “escalating tensions” in the region, and warned: “Any country serving as defensive shield for criminal and aggressive America will be engulfed by the flames of war.”

This week, Iran and the US resumed overnight exchanges of fire after a days-long lull in fighting, although there were no reported strikes overnight Friday to Saturday.

The Middle East war broke out on 28 February when the United States and Israel launched strikes on Iran, which has retaliated with missile and drone strikes across the region.