Violent clashes have continued in the Tunisian town of Siliana, where a police crackdown on protests has left hundreds of people wounded this week, as political instability in the north African country mounts.
Policemen, backed by armoured cars, fired warning shots and tear gas at hundreds of protesters on Friday evening.
The demonstrators hurled rocks and petrol bombs at the security forces, erecting barricades in the town centre and setting some structures on fire.
Thousands had taken to the streets of the impoverished town earlier - demanding the governor's resignation and financial aid in a fourth straight day of unrest - where the authorities have been battling to maintain order.
A representative of the UGTT, Tunisia's main trade union, which had called Friday's demonstration, unsuccessfully urged the protesters to disperse, and appeals for calm from the government were also ignored.
The authorities were unable provide details on the number of people wounded in the latest clashes.
More than 300 people have been wounded in the town, 120km southwest of Tunis, the capital, since Tuesday, when the protesters first took to the streets.
Early on Friday, a "symbolic" march a few kilometres towards Tunis drew a crowd of thousands, who took part on foot, in cars and on motorcycles, chanting: "With our souls and our blood we sacrifice for Siliana."
Protesters told the AFP news agency they would continue their agitation until governor Ahmed Ezzine Mahjoubi steps down, police repression ends and a development programme for the region is put in place.
Precarious living conditions, widespread unemployment and police brutality were driving factors behind the revolution that toppled former president Zine El Abidine Ben Ali.
Amnesty International and the UN High Commissioner for Human Rights Navi Pillay both called on the authorities to end the use of "excessive force" against the protesters in Siliana.
Demonstrations took place in Tunis and Kef, west of the capital, in support of the protesters in Siliana.
On Friday, the streets of the town were littered with stones and the charred remains of barricades from previous unrest.
"We will undertake a symbolic march to show the determination of the people against [economic] marginalisation," Nejib
Sebti, the UGTT regional secretary-general, told AFP earlier, urging the crowd to march "quietly and peacefully".
"We are ready for dialogue but without the presence of the governor," Sebti added.
Hamadi Jebali, the country's prime minister, has refused to sack Mahjoubi, and also rejected calls for his own resignation.
Protesters say they are also angry about police violence during the protests, with some of them treated for shotgun wounds.
"This is what the Ennahda [the ruling party] police did to me," said a man showing injuries to his legs and hips.
Amnesty called for an immediate investigation into claims that shotguns and other firearms were used against them.
Jebali has promised an investigation into the violence, which he said was threatening the country's fledgling democracy as it approaches the second anniversary of the revolution triggered on December 17, 2010.
"We will investigate the possible excessive use of force and the origins of the violence," while demanding accountability from those responsible for "this catastrophe," Jebali said on Thursday.
He also accused secular liberals and religious Salafis of harming the country's economy and international image through their conflict with one another.
The prime minister on Thursday accused opposition parties of sowing disorder and called for the violence in the northern city of Siliana to end.
President criticises government
On Friday, Moncef Marzouki, the president, said in a national address that the government had failed to deal with the crisis adequately, and urged the constituent assembly to quickly ratify a new constitution so that fresh elections could be held by the summer of next year.
The violence in Siliana comes as clashes, strikes and attacks by Salafists have multiplied across Tunisia, plunging the country into a political impasse.
Much of the country's interior suffers from a chronic lack of development and has seen rising discontent over the government's failure to raise living standards.
Al Jazeera's Hashem Ahelbarra, reporting from Tunis, said: "People [are] becoming very disillusioned with the government because of its failure to tackle problems.
"Unemployment is on the rise, and so is poverty. People are asking the government to provide some answers to their demands."
"People who took to the streets in Siliana come from the same deprived regions that were disadvantaged during the last five decades.
"And they are saying that this government, which is supposed to be coming from the will of the people ... is failing us.
"They have been using the same slogans they used against Zine El Abidine Ben Ali."