Tanks were deployed in the Yemeni capital on Monday as top generals pledged allegiance to the "revolution" and the country's main tribal leader demanded President Ali Abdullah Saleh's exit.Tanks took up positions in key locations across Sanaa including at the presidential palace, the central bank and the ministry of defence, but it was unclear what their orders were or who was in command.
In the a series of body blows to Saleh's authority, General Ali Mohsen al-Ahmar, an armoured infantry division commander, announced he had joined the "revolution", along with tribal leader Sadiq al-Ahmar.
"The crisis is getting more complicated and it's pushing the country towards violence and civil war," the general said in a statement broadcast by Al-Jazeera television.
"According to what I'm feeling, and according to the feelings of my partner commanders and soldiers... I announce our support and our peaceful backing to the youth revolution.
One by one, dozens of officers of various ranks stood at the tent city near Sanaa University, where demonstrators have kept vigil since February 21.
Another top general, Nasser Ali Shuaybi, told AFP he had also defected along with 60 military officers and 50 police personnel in Hadramawt province.
Sadiq al-Ahmar, who leads the Hashid tribal federation, the largest in deeply tribal Yemen and a crucial source of Saleh's power, told Al-Jazeera television it was time for the embattled president to make a "quiet exit".