Yemeni government forces have opened fire at protesters in the city of Taiz, wounding dozens, according to witnesses and medics.
Security forces, using machine guns mounted on military vehicles, fired in the air as demonstrators were setting up roadblocks along a main street in the city on Thursday, a Reuters reporter said.
Leaders shouting on megaphones urged protesters to head to the main road to reinforce demonstrators as clashes continued.
The injured were rushed to a field hospital in Freedom Square, the focal point of protests in Taiz.
Protesters calling for the ouster of president Ali Abdullah Saleh have camped out on Jamal Street this week, blocking the key artery.
Meanwhile, in the southern city of al-Baydah, security forces shot dead two protesters and wounded seven others, a witness said, as protesters set fire to the ruling party headquarters.
A day earlier, security forces killed at least 10 demonstrators, two of them in Taiz, bringing the overall
death toll from weeks of protests to more than 160, rights groups have said.