Yemeni security and military officials say Shiite rebels backed by supporters of former President Ali Abdullah Saleh have taken over the country's third largest city of Taiz and its airport.

The seizure on Sunday comes a day after the rebels, known as Houthis, called for a general mobilization against forces loyal to the embattled current president, Abed Rabbo Mansour Hadi. Hadi had just given a defiant speech challenging the Houthis, his first public address since fleeing the capital and establishing a base in the southern city of Aden last month.

Brig. Gen. Hamoud al-Harathi, commander of special forces units based in Taiz, rejected Hadi's legitimacy as president. Meanwhile, thousands demonstrated in Taiz against both the Houthis and Saleh.