Yemen's Iran-backed Houthis targeted an oil refinery on Saudi Arabia's southern Red Sea coast on Tuesday, according to Houthi media, as the group steps up attacks on the kingdom after announcing a maritime blockade.

Yemen, which has been embroiled in more than a decade of civil war, was drawn deeper into the wider Middle East conflict in July after the Houthis ended a 2022 truce with Yemen's Saudi-backed government and resumed attacks on areas held by government forces as well as targets in Saudi Arabia.

The Houthis “targeted the Aramco refinery in Jazan with a number of drones ... in response to airspace violations over the governorates of Saada and Hajjah” in Yemen, the Houthi news agency Saba reported on Tuesday, citing a military source.

Last month, the Houthis welcomed an Iranian aircraft that landed in Yemen's capital Sanaa, triggering a series of tit-for-tat attacks.

The group later announced a maritime blockade targeting Saudi Arabia, which has backed Yemen's government and led a coalition that carried out extensive air strikes on Houthi-held areas during the war.

The United Nations said it was “deeply concerned” about the reported attacks.

“Such attacks risk further entangling Yemen in the wider regional confrontation, at a time when the region is already facing intense pressure and regional trade and energy flows are under severe strain,” said a spokesman for UN Secretary-General Antonio Guterres.

Since the latest escalation in fighting, the Houthis have attacked Saudi tankers in the Red Sea and launched strikes against Yemeni government forces.

The group has also repeatedly targeted Saudi Arabia's oil infrastructure and airports, raising concerns over the potential impact on regional energy supplies and maritime trade.