Several American warplanes crashed in Kuwait on Monday morning, but their crew survived, Kuwait's defence ministry said, as Iran pressed on with a third day of strikes in the Gulf.

"Several US warplanes crashed this morning. Confirming that all crew members survived," a defence ministry spokesman said in a statement, adding that the cause was under investigation.

"Authorities immediately initiated search and rescue operations, evacuating the crews and transporting them to a hospital for medical evaluation and treatment. He noted that their condition is stable," the statement added.

According to TRT World correspondent in Tehran, Iran state TV says a US F-15 jet in Kuwait was downed after Iranian air defence fire.

Earlier in the day, widely-circulated social media footage showed what appears to be a US F-15 warplane crashing in Kuwait, while authorities have not issued any official confirmation about the details of the aircraft.

Footage, widely shared on social media, appears to show a warplane, believed to be an F-15 belonging to the US, going down.

The footage includes images purportedly showing a pilot, who descended by parachute, being taken in a civilian vehicle.