"We will not leave until the fall of the butcher," demonstrators chanted in the capital Sanaa, referring to President Ali Abdullah Saleh. "We will not leave this place until the departure of Saleh and his sons."

The slaughter in Sanaa on Friday afternoon was the bloodiest day in weeks of unrest that have shaken the regime of Saleh, a key US ally in the war against Al-Qaeda in the Arabian Peninsula militants.

Witnesses said pro-Saleh "thugs" rained bullets from rooftops around a square at Sanaa University, which for weeks has been the centre of demonstrations calling for the end of Saleh's 32-year rule.

Many of the victims were shot in the head and more than 120 people wounded, medics said, in scenes that shocked the world and drew diplomatic scorn from Western powers and human rights monitors.

AFP