Police in Yemen have fired bullets and tear gas against anti-government demonstrators near Sana'a University. Medical sources say dozens of people are wounded.
Witnesses say government supporters with knives and clubs also attacked the protesters on Sunday.
Demonstrators have been camped out near the university for days, pressing demands for the resignation of Yemen's President Ali Abdullah Saleh.
Anti-government protests were also reported Sunday in the southern provinces of Taiz and Aden, where a police station was set on fire.
Seven people were reported killed during Saturday's violence in Yemen as the government toughened a crackdown on protesters.
Activists in Yemen began calling for an end to President Saleh's 32-years in power after the uprisings that ousted the longtime presidents of Egypt and Tunisia. Saleh has vowed to remain in office until his term ends in 2013.
On Thursday, Saleh pledged to hold a referendum on a new constitution to foster democratic reforms.
The opposition rejected the offer, saying it was too little too late. On Friday, tens of thousands of anti-government activists gathered in Sana'a for what was described as one of the biggest demonstrations of its kind to date.
Some information for this report was provided by AP, AFP and Reuters.