The Saudi-led military coalition fighting the Iran-aligned Houthi group in Yemen destroyed two explosive-laden boats in the Red Sea on Thursday, its spokesman said.

The two remotely controlled boats belonged to Houthi forces and were threatening navigation, his statement carried on Saudi state news agency SPA said.

They were destroyed 6 km (3.7 miles) south of the Yemeni port of Salif in the early hours of Thursday morning, he said.

Yahya Sarea, a Houthi armed forces a spokesman, said on Twitter the boats were civilian vessels and called the coalition attack a 'major aggression' which violated the Stockholm peace deal, a U.N.-brokered agreement reached in December 2018.

The coalition has previously accused the Houthi movement of trying to attack vessels off the coast of Yemen with unmanned boats laden with explosives.

Merchant ships have been attacked in recent years in the Gulf of Aden and the Bab al-Mandab waterway by armed gangs as well as militant groups such as Al Qaeda in the Arabian Peninsula.

The coalition intervened in Yemen in March 2015 after the Houthis ousted the Saudi-backed internationally-recognised government from the capital, Sanaa, in late 2014. The Houthis, who control most large urban centres, say they are fighting a corrupt system.