Yemeni security officials said two days of clashes between Shiite rebels and Islamist tribesmen in the country's north have killed at least 35 fighters on both sides, the Associated Press reported.

The officials say the Hawthi rebels, who belong to a Shiite sect, have been battling their conservative Sunni rivals from one of Yemen's largest tribes, backed by a local army unit, in Jouf province since Tuesday, July 15.

The two sides are using artillery fire and Katyusha rockets. Jouf is 109 miles (175 kilometers) northeast of the capital, Sanaa, and borders Saudi Arabia.

They officials spoke of condition of anonymity because they are not authorized to speak to media, according to the AP.

Last week's sweep by the Hawthis gained control of the northern Amran province near Sanaa. The rebels already control the province of Saada.