The Iranian-backed rebels, who have targeted Israel and shipping in the Red Sea, said children were among those killed in the strikes ordered by President Trump.

Yemen's Houthi rebels say there have been fresh US strikes against them, with the number of dead rising to 53, including five children. Targets in the Al Jaouf and Hudaydah areas were hit early on Monday, according to the rebel group, while the US Central Command said its forces had continued operations.

The strikes represent the biggest U.S. military operation in the Middle East since Trump took office, and come as the U.S. increases sanctions pressure on Iran while trying to bring it to the negotiating table over its nuclear program.