A leading tribal figure in Yemen announced his resignation from the ruling party on Saturday, signaling a major blow to the embattled leadership of President Ali Abdullah Saleh as demonstrations calling for his resignation continue across the country.

“The Yemeni people would not keep silent on the blood of martyrs shed in Aden and will avenge it,” Sheikh Hussein Al Ahmar said in a speech before a large gathering of tribesmen in northern Amran province, referring to deaths of antigovernment protesters in the southern city of Aden, according to local press reports. He also called for the overthrow the Saleh regime, and the gathering broke out in antigovernment chants.