|Police have been trying to control the situation as violence in the country escalates
A group of senior clerics in Yemen has called for the formation of a national unity government in order to save the country from chaos.
The influential figures are demanding a transitional unity government that would see the opposition represented in key ministries, followed by elections in six months.
They say the move would place Yemen in the same situation as Egypt and Tunisia, without suffering bloodshed.
Their comments on Thursday came amid fresh clashes between thousands of pro- and anti-government protesters in Sanaa, the capital.
Dozens of pro-democracy protesters, including two suffering gunshot wounds, have been injured in the confrontations.
"Police are trying to form lines to separate protesters and pro-government supporters - but they're also attempting to disperse crowds with live ammunition, a sign of the very tense situation in the capital ahead of calls for tomorrow's 'Friday of Fury'," said Hashem Ahelbara, Al Jazeera's correspondent in Sanaa.
Loyalists of the government wielding batons and daggers chased a group of protesters meeting at the city's university, witnesses said. At least five people were injured in the violence there.
Municipal vehicles ferried sticks and stones to the pro-government side, witnesses among the estimated 6,000-strong crowd said.
"President Ali Abdullah Saleh is meeting daily with powerful tribal chiefs in areas surrounding the capital, telling them he needs their support for this crucial moment," said Ahelbara.
"He has struck a very harsh tone, describing the protesters as 'anarchists'.
"His entourage is telling media that the situation here is very different to Egypt and Tunisia - and if this country degenerates into violence, it could end up in a very, very difficult situation.
"People here are armed across the country. Tribes have caches of weapons - and the situation here could become much, much worse."
Ahelbara said that distrustful protesters have rejected the president's calls to wait for elections in 2013, saying: "The only way is for us to keep fighting in the streets to bring about the dramatic changes that have taken place in Tunisia and Egypt." Demonstrators are also continuing to protest in the southern city of Taiz.
On Wednesday, two protesters were killed Aden, a southern port city, while protesting against the rule of Ali Abdullah Saleh, the president.
Unrest has swept the streets of Yemen for the past one week, with anti-government protesters clashing with government supporters and security forces.
In the face of the unrest, Saleh has postponed a visit to the US that had been planned for later this month, after the opposition agreed on Sunday to resume talks suspended since October.
Eyeing protests that brought down the presidents of Tunisiaand Egypt, Saleh, in power since 1978, pledged earlier this month not to stand in the next presidential elections. He also vowed not to pass on the reins of power to his son.
But his pledges apparently have done little end the protests.
Of the 23 million people in Yemen, 40 per cent live on less than $2 a day and a third suffer chronic hunger.