Attacks on shipping in the southern Red Sea on Sunday heightened fears of the conflict spreading.

The US Defence Department has said three commercial ships were attacked by Yemen’s Iran-allied Houthi movement in international Red Sea waters, and a US destroyer operating in the area shot down three drones as it responded to distress calls.

A Houthi spokesperson said its navy had attacked two Israeli ships in the Red Sea with an armed drone and a missile on Sunday, though an Israeli military spokesman said the two ships had no connection to Israel.