|President Saleh's speech on Thursday night fuelled the sense of defiance on the streets of the capital [Al Jazeera]
Yemen's president, Ali Abdullah Saleh, has offered to stand down - but only to hand over power "to capable, responsible hands," he says.
The longtime leader addressed crowds shown on state TV and said he was ready to meet with protesters, as tens of thousands gathered in a "day of departure" rally.
But he also said those demanding his resignation had been influenced by the Houthis - a powerful armed clan demanding greater autonomy in their region of the country - and drug dealers.
On Thursday night, opposition groups rejected Saleh's offer to quit after a presidential election at the end of the year, stepping up efforts to remove him from power.
Yassin Noman, head of Yemen's opposition coalition, dismissed Saleh's earlier offer as "empty words" and a spokesman said the umbrella coalition would not respond.
"No dialogue and no initiatives for this dead regime," opposition spokesman Mohammed al-Sabry said on Thursday.
Protesters are demanding a new constitution and the dissolution of parliament, local councils and the notorious state security agencies - as well as the immediate resignation of President Saleh.
Tensions ratcheted higher ahead of a planned rally that has been dubbed a "Friday of Departure", as presidential guards loyal to Saleh clashed with army units backing opposition groups demanding his resignation.
Our special correspondent, reporting from Change Square - where 52 protesters were killed last Friday - said: "People here are concerned and fear a repeat of last Friday's violence. There are two or three makeshift medical centres set up around the square, and people are trying to get as many medical supplies into them as possible.
Tens of thousands of people entered the square and its surrounding area in front of Sanaa university, for Friday prayers, ahead of the planned protest. The mood there was initially positive, our correspondent said.
"In the past seven days, a lot of momentum has gathered behind these protesters. And if people do make the journey from here to the presidential palace, that will certainly be a flashpoint - and further violence is likely," added our reporter, who we are not naming for security reasons, after Al Jazeera's office was raided and its staff attacked this week.
General Ali Mohsen has thrown his weight behind the opposition and has sent troops to protect pro-democracy protesters in Sanaa. He said the options before Saleh were now few, and criticised what he described as Saleh's "stubbornness", but said the armed forces were committed to protecting protesters.
The general also said he had no desire to take power, as fears grew of a major confrontation between rival military units in the capital Sanaa or elsewhere.
He said military rule in Arab countries was outdated and that the people would decide who would govern them in the framework of a modern, civilian state.
"Ali Mohsen as an individual has served for 55 years and has no desire for any power or position," he told Reuters.
"I have no more ambition left except to spend the remainder of my life in tranquility, peace and relaxation far from the problems of politics and the demands of the job."
Mohsen, commander of the northwest military zone and formerly Saleh's close ally from the al-Ahmar clan, is the most senior military officer to back the protests, and his move on Monday triggered a stream of defections in the military and government.
Saleh has offered amnesty to defecting troops, calling their decisions "foolish acts", taken in reaction to last Friday's deaths.
In his address, Saleh promised to transfer power peacefully, but gave no indication of the timing or conditions.
"There is no way by any means or circumstance for the political system to offer itself to the gallows," Saleh said.
"By all means come for political dialogue, and power can be transferred peacefully through constitutional institutions."
He also vowed to defend himself by "all possible means" against the escalating campaign seeking to unseat him.
Protesters who have been encamped in their thousands outside Sanaa University for about six weeks have hardened in their attitude towards Saleh, rejecting any idea of his remaining.
They hope Friday's protests could bring hundreds of thousands onto the streets.
They said on Thursday they were tired of the drip-feed of concessions.
"This talk is aimed at delaying the announcement of the death of the regime. The opposition does not need to respond," spokesman Mohammed al-Sabry said.
Washington, which has urged US citizens to leave Yemen, warned those remaining to stay away from demonstrations on Friday.
Britain said it had drawn up plans for a possible military evacuation of its citizens who remain in Yemen.
Foreign Secretary William Hague told parliament he had reports that oil companies were withdrawing their staff, and part of the British embassy staff was being withdrawn from Sanaa ahead of Friday's protests.
Source: Al Jazeera and agencies