By Khaled Yacoub Oweis and Mohammed Ghobari
SANAA (Reuters) - The killing of an anti-government protester has hardened attitudes against President Ali Abdullah Saleh's 32-year rule, said opposition supporters, who vowed on Wednesday not to abandon their protests in the face of violence.
Witnesses said Abdullah Hameed Ali, 28, was shot in the head late on Tuesday after policemen and security agents fired on a group setting up tents in front of Sanaa University -- an area that has become the focal point of the civil unrest.
"They charged at us with their guns and bats and started shooting," said Raafat Baji, who was one of around 80 people injured in the attack.
The state news agency Saba blamed the shooting on gunmen linked to a tribal leader and said police were hunting for the culprits. Opposition figures dismissed this and said the attack showed Saleh was getting desperate.
"These attacks signal the beginning of the disintegration of the regime in the face of the youth revolution," said Mohammed Qahtan, a spokesman for Yemen's umbrella opposition coalition.
Yemen, a neighbor of oil giant Saudi Arabia and the poorest country on the Arabian Peninsula, has seen a wave a protests in recent weeks inspired by the turmoil in Tunisia and Egypt.
Almost 30 people have died in the unrest and analysts have warned that the situation could degenerate rapidly.
"This is a further indication of the escalation of violence in Yemen as the protests continue," said Theodore Karasik a security analyst at the Dubai-based INEGMA group.
"Yemen is following the Libya model in that this is tribal-based, whereas ... Egypt was secular," he added.
Saleh was battling to maintain order in Yemen even before this year's unrest, struggling to quell rebellions in the north and south, while also helping the United States combat al Qaeda's active Yemeni operations.
The Saudi-backed president has offered to form what he termed as a unity government, but has refused to bow to demands to remove his relatives from the security apparatus or to step down himself before his term ends in 2013.
Police cars and armored vehicles with armed soldiers and water cannon deployed across the capital on Tuesday and continued to surround the area where protesters are gathered.
"The situation is still tense, and we're expecting more attacks," said Mohammed al-Sharfi, one of the activists who has been camping out at the Sanaa protests.
Ali Omrani, a major tribal figure who was an ally of the president until this month, said Tuesday's university attack would only strengthen sentiment against Saleh.
"The president can either leave or keep spilling blood. I hope he retains his dignity and spares Yemen more tragedy after decades of bloody conflicts, most of which could have been avoided," he said.
(Additional reporting by Mohamed Sudam and Erika Solomon in Dubai; Editing by Elizabeth Fullerton)
(Writing by Crispian Balmer; editing by Elizabeth Fullerton)