At least one person is killed and dozens are wounded as Yemen security forces storm a protest site where thousands of pro-democracy protesters have been camped out for weeks, demanding the ouster of the country's leader.
In a pre-dawn raid on Saturday, police are said to have used tear gas and hot water mixed with gas to disperse the demonstrators.
Al Jazeera's Hashem Ahelbarra, reporting from the capital Sanaa, said that despite the clashes, protesters remain undeterred.
"This was demonstrated in the largest protest yet on Friday, calling on president Ali Abdullah Saleh to step down," he said.
Al Jazeera can also confirm that Yemeni police are not allowing ambulance vehicles to enter Sanaa University square to treat the injured.
Tens of thousands of protesters marched on the streets, drawing record crowds in Sanaa in a continuing push to demand the ouster of the Yemeni president who has been in power since 1978.
Violence
Thousands of Saleh loyalists also crammed the capital's Tahrir Square, carrying pictures of the veteran leader.
Protests, however, turned violent in the southern port city of Aden, where three people were wounded by gunfire and six overcome by tear gas as police tried to disperse the crowd.
Unidentified armed men on Friday killed four soldiers on patrol east of Mukalla city in Hadhramaut province, in southeast Yemen.
Security sources accused al-Qaeda operatives of being behind the attack.
A wave of unrest has weakened Saleh's decades-long grip on his impoverished nation, with about 30 people killed since January.
Meanwhile, a top White House aide told Saleh on Friday the United States welcomed his steps to resolve the political crisis in Yemen and urged opposition groups to heed calls for talks.
"All sectors of the Yemeni opposition should respond constructively to president Saleh's call to engage in a serious dialogue to end the current impasse," John Brennan, the top counterterrorism adviser told Saleh in a telephone call, the White House said in a statement.
US support
"Brennan noted that the government and the opposition share responsibility for achieving a peaceful resolution of the crisis. He also stated that a commitment by all sides to participate in an open and transparent process that addresses the legitimate concerns of the Yemeni people provides an orderly path to a stronger and more prosperous nation."
On Thursday, Saleh bowed to pressure after a month of violent protests, pledging to devolve power to parliament. But this was swiftly rejected as too late by the opposition.
He also ordered his security forces to ensure the safety of anti-government protesters after weeks of unrest in which some 30 people have been killed, part of a wave of popular unrest across the Arab world.
He said he would hold a "referendum before the end of the year on a new constitution clearly stipulating the separation of powers" between the president and the parliament.
The new charter would "install a parliamentary regime giving all executive powers to a government elected by parliament," he added.
Yemen is a crucial partner of the United States in the fight against
al-Qaeda in the Arabian Peninsula (AQAP), which has plotted attacks against US targets from its bases in the country's tribal regions.
It is also battling sectarian and secessionist violence, which undermine stability and development in one of the poorest countries in the region.
Source:
Al Jazeera and agencies