A missile fell near a ship southwest of the Yemeni port city of Aden, maritime security firms said on Sunday, in the second such incident in less that 24 hours.

The attack was not immediately claimed, but it coincides with a campaign by Yemen's Iran-backed Huthis against ships the rebels say are linked to Israel amid the Gaza war.

British security agency United Kingdom Maritime Trade Operations said a "missile impacted the water in close proximity" to the ship.

"No damage to the vessel reported and crew reported safe," it said.

Security firm Ambrey also reported a "projectile" hitting the water near the ship, advising vessels in the vicinity to "exercise caution".

The attack comes hours after two missiles targeted a ship southwest of the Yemeni port city of Hodeidah, according to both UKMTO and Ambrey.

One missile was intercepted by US-led coalition forces and the second missed the ship, according to UKMTO.

Huthi rebels have launched dozens of missile and drone strikes on shipping in the Red Sea and the Gulf of Aden since November, saying their actions are in solidarity with Palestinians during the Gaza war.

Most of the attacks have been by drone or missile, but in November helicopter-borne Huthis seized the vehicle-transporter Galaxy Leader and its crew.

The United States, which leads an multi-national flotilla intended to protect Red Sea shipping, has since mid-January launched repeated attacks on Huthi targets in Yemen.

British warplanes have also taken part in several of the strikes.

In a televised speech on Thursday, Huthi chief Abdul Malik al-Huthi said 37 people had been killed in more than 400 strikes by the US and Britain on Yemen since January.

"During these operations and attacks, 37 martyrs died and 30 others were wounded," he said, without specifying if the casualties were civilians or combatants.

The rebel leader vowed to continue strikes on Red Sea shipping, saying his fighters had launched 34 attacks over the past month.