Iranian-backed Houthi rebels struck a military camp for government forces in southern Yemen on Monday, killing at least 20 soldiers, Yemeni military officials said, in one of the deadliest attacks in the recent surge in fighting.

The rebels fired ballistic missiles on the al-Alam military camp in the southern province of Shabwa in an attack that also wounded at least two dozen troops. The military officials with the internationally recognized government of Yemen spoke on condition of anonymity because they were not authorized to brief the media.