More than 40,000 Americans have returned to the US from the Middle East since the start of joint US-Israeli attacks on Iran, the State Department announced Tuesday.

Assistant Secretary Dylan Johnson said the agency completed more than two dozen charter flights and directly assisted over 27,000 Americans abroad with security guidance and travel assistance.

Ground transport operations and charter flights were continuing as commercial flight availability across the region gradually improved, he added.

The figures mark an increase from the 36,000 evacuees reported Monday.

"The State Department will continue to actively assist any American citizen who wishes to depart the Middle East, to do so," he said.

The escalation in the Middle East flared when Israel and the US launched a joint attack against Iran on Feb. 28, reportedly killing more than 1,200 victims to date, including Supreme Leader Ayatollah Ali Khamenei.

Tehran has retaliated with drone and missile strikes targeting Israel, along with Gulf countries hosting US military assets.

Eight US service members have been killed since the campaign began. (AA)