SANAA, Yemen (AP) — Yemeni security officials say Houthi rebels have detained seven local employees of the International Medical Corps, accusing them of spying for foreign intelligence.

They say Friday the Houthis raided a hotel the humanitarian group was using in Ibb province, taking the employees to a prison in the capital, Sanaa.

The rebels, from a Shiite sect based in the north, stormed south into the capital in late 2014, leading the president to flee several months later. In March 2015, a Saudi-led coalition launched an air and ground campaign to overthrown the rebels, but it's been unable to advance much from a southern foothold.

The war is in stalemate, and the U.N. says some 50,000 civilians have been killed or wounded.

The officials spoke anonymously as they weren't authorized to brief journalists.