Yemen's Iran-backed Houthi group said on Wednesday it would keep up attacks on US and British warships in the Red Sea in what it called acts of self-defense.

In a statement, the group's military spokesperson said all American and British warships participating in "aggression" against its country were targets.

The Houthi announcement came after another Iranian proxy force in Iraq, Kataib Hezbollah, announced on Tuesday that it was suspending attacks against US forces.

The Houthis, who control the most populous parts of Yemen, have been attacking ships in and around the Red Sea, saying they are acting in solidarity with Palestinians in the Gaza war. The attacks began in mid-November after Iran’s ruler Ali Khamenei urged Muslim countries to blockade Israel.

The US and Britain have launched retaliatory strikes on Houthi targets in Yemen and returned the militia to a list of terrorist groups as turmoil from the Israel-Hamas war spreads through the region.

The Houthis attacks on the Red Sea have added an economic element to the turmoil by targeting shipping in and around the Red Sea.

The Houthis fired missiles at US warship USS Gravely, the statement added. On Tuesday night, the US military's central command said they had shot down one anti-ship cruise missile fired from Yemen towards the Red Sea with no damage reported.

The Houthi attacks have primarily targeted container vessels. Many fuel tankers have kept using the route.

Some shipping companies have suspended transits through the Red Sea and taken much longer, costlier journeys around Africa to avoid being attacked.

Houthis say they will persist with their military operations until a ceasefire is agreed in Gaza.