A vessel sailing off southern Yemen reported an explosion nearby on Sunday, a British maritime security agency said, the latest incident as Huthi rebels have attacked shipping on the vital Red Sea route.

United Kingdom Marine Trade Operations said a commercial ship "has reported an explosion in close proximity to the vessel", causing no casualties or damage.

The blast hit as the ship was sailing "85 nautical miles east of Aden" in Yemen, and the vessel was "proceeding to its next port of call", said UKMTO, which is run by the Royal Navy.

It did not identify the vessel.

There was no immediate claim of responsibility for the reported attack, which comes after Yemen's Iran-backed Huthis have threatened to expand the harassment campaign which has disrupted global trade.

The rebels have launched dozens of missile and drone strikes on shipping in the Red Sea and the Gulf of Aden over the past four months, actions they say are in solidarity with Palestinians.

The Huthis say they are targeting Israel-linked shipping as part of an "axis of resistance" of Iran allies in protest at Israel's war against Hamas in the Gaza Strip.

The United States, which leads an international coalition meant to protect Red Sea shipping, has since mid-January struck Huthi targets in Yemen.

The US Central Command said on Saturday its forces had "destroyed five unmanned surface vessels and one" drone in Huthi-controlled areas of Yemen.

CENTCOM earlier said it had shot down a drone fired by the Huthis toward the Red Sea.

Such exchanges have become frequent in the area, sending shipping insurance costs soaring and prompting many firms to detour around the southern tip of Africa.

On Thursday rebel leader Abdul Malik al-Huthi said the group would expand their attacks to ships taking the longer route around Africa's Cape of Good Hope.