US and UK strikes on rebel-held Yemen have marked a sharp rise in tensions around the Red Sea, where Iran-backed Houthi insurgents have been attacking shipping.

The Houthi attacks since November, which the group says target vessels linked to Israel and are in support of Gaza, have disrupted shipping in the vital route which normally carries around 12 percent of global maritime trade.

US and UK forces strike 60 Houthi missile and radar targets at 16 locations in rebel-held Yemen, the US military says, in a barrage involving more than 150 precision-guided munitions.

Five people are killed and six wounded, according to Houthi officials. In retaliation, the Houthis fire “at least one” missile without hitting any target.

The rebels declare American and British interests as “legitimate targets” after the overnight strikes.

A further US strike hits the rebels’ Al-Dailami airbase in the capital Sanaa, the US military says in what it calls a “follow-on action” related to the previous day’s strikes.

The Houthis warn they will continue attacking ships in the Red Sea.