The strike on a Houthi radar site comes a day after scores of attacks across the country heightened fears that Israel's war with Palestinian militant group Hamas could engulf the wider region.

The Iran-backed militants' official media earlier said the Al-Dailami airbase in Yemen's rebel-held capital of Sanaa had been struck. 

The Houthis, who have carried out weeks of attacks on Israel-linked shipping in protest at the Israel-Hamas war, warned that US and British interests were "legitimate targets" after the first volley of strikes.

Britain, the United States and eight allies said strikes carried out on Friday had aimed to "de-escalate tensions", but the Houthis vowed to continue their attacks.

"All American-British interests have become legitimate targets" following the strikes, the rebels' Supreme Political Council said.

Hussein al-Ezzi, the rebels' deputy foreign minister, said the United States and Britain would "have to prepare to pay a heavy price".

The rebels have controlled much of Yemen since a civil war erupted in 2014 and are part of an Iran-backed "axis of resistance" against Israel and its allies.

Violence involving Iran-aligned groups in Yemen, Lebanon, Iraq and Syria has surged since the war in Gaza began in early October.

UN chief Antonio Guterres called on all sides "not to escalate" in the interest of regional peace and stability, his spokesman Stephane Dujarric said.

The UN Security Council held an emergency meeting on the strikes Friday, days after adopting a resolution demanding the Huthis immediately stop their attacks on ships.

At the meeting, US Ambassador Linda Thomas-Greenfield warned that no ship was safe from the threat posed by Houthi rebels to shipping in the Red Sea.

Russian ambassador Vassili Nebenzia denounced the "blatant armed aggression" against the entire population of the country.