US and British air strikes carried out early Friday against Huthi targets in Yemen over recent attacks on Red Sea shipping were "necessary and proportionate", UK Prime Minister Rishi Sunak said.

"Despite the repeated warnings from the international community, the Houthis have continued to carry out attacks in the Red Sea," Sunak said in a statement, using an alternative spelling for the Huthis.

"We have therefore taken limited, necessary and proportionate action in self-defence, alongside the United States... to degrade Houthi military capabilities and protect global shipping," he said.

Sunak's statement followed comments by US President Joe Biden about the strikes carried out against the Huthis, who control wide areas of Yemen.

Biden described the joint strikes as "defensive" and warned of further measures if the Iran-backed rebels kept attacking Red Sea shipping.

He said Australia, Bahrain, Canada and the Netherlands had also provided non-operational support.

The Huthis have stepped up attacks in recent weeks on shipping in the Red Sea, a vital waterway through which 12 percent of world trade flows.

Huthi television channel Al-Massirah said the air strikes hit the capital Sanaa as well as the cities of Hodeida and Saada.

US and British forces this week shot down 18 drones and three missiles fired by Huthi rebels in the Red Sea in what Washington called a "complex Iranian-designed" attack.

UK Defence Secretary Grant Shapps said on social media platform X that four Royal Air Force Typhoon fighter jets had taken part in Friday's strikes against Huthi targets alongside US forces.

Sunak described the Huthis' actions as "irresponsible" and "destabilising" and said their attacks were "driving up commodity prices".

"This cannot stand. The UK will always defend freedom of navigation and the free flow of trade," he said.