US and UK naval forces have shot down 21 drones and missiles fired by Yemen-based Houthis towards international shipping lanes in the southern Red Sea, the United States says.
The United Kingdom's defence minister said it was the largest attack in the area by the militants to date as the three-month-long war between Israel and Hamas in Gaza spills over into other parts of the Middle East.
US Central Command said no injuries nor damage were reported, adding that this was the 26th Houthi attack on commercial shipping lanes in the Red Sea since November 19.
The Houthis, who control most of Yemen, have been targeting the route to show their support for Hamas, a Palestinian Islamist group.
The attacks have seriously disrupted international commerce on the key route between Europe and Asia that accounts for about 15 per cent of the world's shipping traffic.
Many shipping companies have been forced to reroute their vessels, taking the longer journey around Africa, although several oil majors, refiners and trading houses have continued to use it.
US Central Command said 18 drones, two anti-ship cruise missiles and one anti-ship ballistic missile were shot down by the two navies in the incident.
UK defence minister Grant Shapps said on Wednesday: "Overnight, (Royal Navy ship) HMS Diamond, along with US warships, successfully repelled the largest attack from the Iranian-backed Houthis in the Red Sea to date."
Shapps repeated a warning from the UK and its allies, including the US and Germany, that the attacks were unacceptable, telling the militant group that it would "bear the consequences" if they continue.
"We will take the action needed to protect innocent lives and the global economy," he said.
The Iranian-aligned Houthis have vowed to continue attacks until Israel halts the conflict in Gaza, and warned they would would attack US warships if the militia group itself was targeted.
German shipping group Hapag Lloyd said on Tuesday it would continue to avoid the Suez Canal and around the Cape of Good Hope for security reasons while its Danish rival Maersk has said it would avoid the route "for the foreseeable future".
Retailers across the world have also been stocking up on goods before China's Lunar New Year holiday and seeking air or rail alternatives to avoid empty shelves this northern spring.
