|Opposition groups protesting for months have called for Saleh to step down [EPA]
Yemen's President Ali Abdullah Saleh has called on the opposition to join talks.
"We call on the opposition to consult their consciences and come to dialogue and reach an agreement for security and stability of the country," Saleh said in an address to thousands of his supporters on Friday.
"These crowds are a clear message to those inside and outside the country ... on constitutional legitimacy."
Thousands of pro- and anti-government demonstrators are holding rival rallies in Yemen including in the capital Sanaa.
Opposition groups, protesting for months, have called for Saleh to step down over the country's lack of freedoms and extreme poverty.
Activists distributed leaflets calling on people to stop paying taxes, electricity and other bills to the government in a campaign of civil disobedience to force Saleh out.
Strikes in schools and government offices began in the southern city of Aden last week.
Electricity supply was hit in cities including Sanaa, Taiz, Hudaida and Ibb after tribesmen attacked a main power plant, an official said, accusing them of acting on behalf of opposition parties.
Thirteen protesters were hurt in Taiz when Saleh loyalists opened fire on some of tens of thousands who took to the streets after Friday prayers, witnesses said.
The opposition has set a two-week deadline for the President to step aside, rejecting a Saudi-brokered, Gulf-backed initiative to end the country's political turmoil.
"We have renewed our emphasis on the need for speeding the process of (Saleh) standing down within two weeks. Therefore we will not go to Riyadh," Mohammed al-Mutawakkil, a prominent opposition leader, said on Thursday, referring to the proposed talks in the Saudi capital.
Meanwhile, Yemeni religious scholars and tribal leaders have said they would support the demands of the youth revolution and called on President Saleh to step down immediately.
In a statement issued late on Thursday in the capital Sanaa, they said the peaceful demands of protestors should be met and urged "the immediate stepping down of the President of the Republic and the dismissal of all his relatives from the military and security apparatus of the state".
Violence during protests
On Wednesday five people were killed in the Yemeni capital Sanaa as forces loyal to a defected army general and pro-government fighters clashed, Al Jazeera's correspondents said.
Thousands of pro- and anti-government demonstrators have held rival rallies
Two more people were killed on Wednesday in the southern city of Aden in clashes between security forces and anti-regime demonstrators.
The defected general, Ali Mohsen, a kinsman of Saleh who has thrown his weight behind the opposition and whose military units are protecting protesters in Sanaa, has welcomed a mediation proposal by the six-nation Gulf Co-operation Council (GCC) to end the unrest.
But on Tuesday, tens of thousands of Yemenis staged protests against the proposal, with many saying it offers Saleh, in power since 1978, an immunity from prosecution.
Up to 100 people have been killed in the unrest which shows no sign of subsiding.
Source: Al Jazeera and agencies