US and UK forces launched a fourth round of strikes against targets in Yemen, Houthi media said Thursday, as the Iran-backed rebels vowed to continue attacking Red Sea shipping.

"We will continue to target Israeli ships heading to the ports of occupied Palestine, no matter how the American-British aggression tries to prevent us from doing so," a Houthi military official told the rebels' Al-Masirah TV.

Al-Masirah and Houthi news agency Saba.net said US and UK strikes had hit several targets in Yemen, including the port city of Hodeida and the city of Taez, the fourth round of strikes in the past week.

US media, including CBS and CNN, quoted US officials as saying another round of strikes had been carried out against an unspecified number of Houthi targets in Yemen.

The Iran-backed rebels' promise to continue attacking shipping in the Red Sea is in support of Palestinians in the Gaza Strip, where Israel is battling the Islamist militant group Hamas.

It came after a US announcement that the Houthis had been put back on its list of "terrorist" entities because of their attacks in the Red Sea.

The United States and Britain hit nearly 30 sites in Yemen with more than 150 munitions last week, while US forces later attacked a Houthi radar site.

The Houthis said late on Wednesday they had attacked a ship with a drone off Yemen. The United Kingdom Maritime Trade Operations (UKMTO) security agency said a drone hit a vessel in the Gulf of Aden.

While a Houthi spokesman said the group had targeted a US ship, British maritime risk management company Ambrey said the vessel was a Marshall Islands-flagged bulk carrier.

The UKMTO said a fire on board the ship had been extinguished and the "vessel and crew are safe".