UNITED NATIONS –  The U.N. special envoy to Yemen is warning that the dangerous military escalation following a breakdown in the cease-fire between government supporters and Shiite rebels is fueling the spread of al-Qaida and the Islamic State extremist group.

Ismael Ould Cheikh Ahmed told the U.N. Security Council on Wednesday that the two militant groups "continue to wreak havoc in significant parts of Yemen."

He pointed to Monday's suicide bombing by the Islamic State group in the southern city of Aden.

While the Yemeni army's growing ability to confront extremist groups is encouraging, Cheikh Ahmed said "the absence of the state in many parts of Yemen, in addition to the chaos created by war, will continue to facilitate the expansion of these terrorist groups which represents a real threat to the region."