Four crew members of a small cargo ship were killed when it was hit by the Houthis on Tuesday, Yemen's transport ministry said, adding the dead also included an Indonesian.

The fatalities aboard the Egyptian-owned Tihamah marked the first deaths in a Houthi strike on shipping since the Iran war began on February 28.

The Houthis said the ship was carrying Saudi military equipment. There was no immediate comment from Saudi authorities.

The Houthis declared on July 20 they would impose a naval blockade against Saudi Arabia in the Red Sea in response to what they described as a Saudi siege on Yemen, an allegation Riyadh has denied.

Since then, they have been launching attacks against Saudi Arabia and Yemen's Mocha and Marib, which are controlled by the Saudi-backed, internationally recognized government based on Aden.

(Reporting by Mohammed Ghobari, Writing by Nayera Abdallah, editing by Chris Reese and Alex Richardson)