The site of a bomb blast outside the Saba News Agency in Sanaa, June 25.

SANAA — Shelling by Yemen’s Houthi militia killed four soldiers from Saudi Arabia and the United Arab Emirates stationed on Yemen’s border with the kingdom, Saudi state media reported on Thursday.

The Houthis have stepped up attacks on Saudi border posts in recent weeks, despite three months of bombardment by a Saudi-led coalition intent on restoring Yemen’s government in exile.

Two soldiers from the Royal Saudi Land Forces, one from the kingdom’s Border Guards, and a UAE officer were killed on Wednesday in three incidents along the border, a mostly mountainous area.

The Houthis and their allies in Yemen’s army have managed to hold most of the populated western part of the country against armed groups in Aden, Taiz, Dhalea and Marib backed by coalition air strikes.

But a spate of bombings in the Houthi-controlled capital continued on Thursday, as a remote controlled bomb detonated outside the state news agency according to residents, killing a Houthi fighter and wounding two others.

Saudi Arabia’s coalition of Arab countries wants to force the Houthis and Saleh to quit captured areas, return seized arms and let President Abd-Rabbu Mansour Hadi return from his Riyadh exile in line with U.N. Security Council resolution 2216.

However, neither side appears ready to make concessions, causing the collapse of U.N.-sponsored talks last week. Aid groups say Yemen’s humanitarian crisis is worsening as a result of fighting and a coalition embargo.