ADEN: At least 26 fighters were killed in clashes Monday between pro-government troops and rebels over control of an oil-rich region east of the Yemeni capital, military sources said.

“Pro-government forces launched a military operation today to retake Sirwah,” a loyalist military source said of the only part of Marib province still held by the rebels who have controlled nearby Sanaa since September 2014.

Clashes and air raids by the Arab-led coalition backing Yemen’s internationally recognized government “killed 16 rebels and left dozens wounded,” the source said.

Ten pro-government soldiers were killed and 12 wounded in the fighting, he added.

Loyalist forces recaptured hills overlooking Sirwah, military sources said.

Marib has seen fierce battles between forces loyal to President Abed Rabbou Mansour Hadi and Houthi rebels and their allies.

If they controlled Marib, loyalist forces could advance from the east toward Sanaa.