US Defence Secretary Lloyd Austin, who is on a tour of the Gulf, has indefinitely postponed a visit to Saudi Arabia, the Pentagon said Wednesday, citing "scheduling issues."

"The Secretary's trip to Saudi Arabia has been postponed due to scheduling issues. He looks forward to rescheduling at the soonest opportunity," a defence department official told AFP.

Austin travelled to the Gulf region earlier this week, a week after the chaotic US withdrawal from Afghanistan ended.

He first went to Doha, Qatar with Secretary of State Antony Blinken to visit the main base for the massive airlift set up by the United States out of Kabul. The United States and its allies evacuated some 123,000 people, mostly Afghans who fear Taliban retribution, in the final days of the 20-year US war that President Joe Biden ended last month.

Austin then travelled to Kuwait, where he met Wednesday with the country's leaders. He thanked them for their "critical role" in supporting the evacuations from Afghanistan, he said on Twitter.

He also travelled to Bahrain, where he praised the "heroic work" of the US Navy personnel stationed there during the Afghanistan evacuations, which Austin called the "largest military airlift mission in history."