SANAA A prominent Yemeni tribal figure resigned from President Ali Abdullah Saleh's ruling party on Saturday and called for the veteran Arab leader's overthrow, a day after fierce clashes in Aden killed seven people.
Hussein al-Ahmar announced his resignation at a rally of tens of thousands in the town of Amran, 30 miles northwest of the capital Sanaa, held to demand the end of Saleh's 32-year rule.
Twenty-four people have been killed since February 17 in daily protests against Saleh across the impoverished Arab state, though unrest has been most intense in the once-independent south where many people resent rule from the north.
"I announce my resignation from the General People's Congress ... and I call on all noble Yemenis to overthrow the regime," Ahmar told the rally, dubbed the Festival of Freedom and Change. "The regime must go, so we can build a nation based on (civil) institutions."
Ahmar belongs to the same powerful tribal federation as Saleh and his father Abdullah, who died in 2007, was considered Yemen's second most powerful figure after the president.
Hussein resigned once before from Saleh's party, two years ago, but rejoined in December and was offered a senior party post, which he declined. One of his brothers is a long-time critic of Saleh, while another is deputy speaker of parliament.
Saleh, a U.S. ally against a Yemen-based al Qaeda wing that has launched attacks at home and abroad, is struggling to end protests flaring in the Arabian Peninsula's poorest state.
Opposition to Saleh, who was previously confronting an on-off Shi'ite Muslim revolt in the north and a secessionist insurgency in the south, has now spread across the country, galvanised by successful uprisings in Egypt and Tunisia.
ACCESS TO HOSPITAL BLOCKED
Doctors said five more people died on Saturday after being shot during Aden's anti-government protests on Friday, bringing to seven the number killed in the clashes with security forces. About 50 people were wounded.
Amnesty International said it received reports that security forces refused to allow residents to take the injured to hospitals.
"Security forces fired on protesters from armoured vehicles, as well as attacking houses where protesters were believed to have been seeking shelter," Amnesty said in a statement.
"Events in Yemen are taking a serious turn for the worse and the Yemeni security forces are showing reckless disregard for human life," said Philip Luther, an Amnesty regional official.
"The Yemeni authorities have a duty to ensure that those injured receive medical treatment. They must on no account block access to urgently needed medical assistance, particularly when people's lives may be at risk," he said.
On Friday tens of thousands of loyalists and opponents held rival rallies in Sanaa, while 10,000 people staged a sit-in in the city of Taiz, 200 km (125 miles) south of the capital, and protests erupted across the southern port city of Aden.
Protesters continued a sit-in outside Sanaa University, where huge crowds gathered on Friday, chanting the slogan which has echoed around the Arab world since the Egyptian and Tunisian revolts: "The people demand the downfall of the regime."
Saleh supporters chanted their loyalty to a man they see as holding the impoverished tribal nation together. "The creator of unity is in our hearts. We will not abandon him," they cried.
Saleh has promised to step down when his term ends in 2013 and not hand power to his son, though he has backed out of similar pledges in the past.
Nine members of parliament resigned from Saleh's ruling party on Wednesday in protest against what they said was government violence against protesters, but the president still has the support of around 80 percent of parliamentarians.
(Additional reporting by Mohammed Mukhashaf in Aden and Mohamed Sudam in Sanaa; Writing by Dominic Evans; Editing by Alistair Lyon and Jon Boyle)