Cairo: Saudi forces and Yemen’s Al Houthi militia traded heavy artillery fire which blew up part of the main border crossing between the two countries overnight, residents said on Sunday, an escalation of the two-month war.

The Haradh border crossing, the largest for passengers and goods between the world’s top oil exporter, Saudi Arabia, and its impoverished neighbour, was evacuated amid shelling which razed its departure lounge and passport section, witnesses said.

Residents of several Yemeni villages in the area left their homes and fled from the frontier, which has turned into a front line between the kingdom and the Iran-allied rebels.

Saudi Arabia has led an Arab coalition bombing Al Houthis and backing southern Yemeni fighters opposing the group and loyal to the exiled government in Saudi Arabia headed by President Abd Rabbo Mansour Hadi.

Gulf states believe Al Houthis are a proxy for influence by their arch rival Iran, but their campaign has yet to reverse the militia’s battlefield gains.