By Cynthia Johnston and Mohammed Ghobari
SANAA (Reuters) - Yemen's opposition stepped up efforts to remove President Ali Abdullah Saleh on Thursday, dismissing his offer to stand down after a presidential election at the end of the year.
Tensions ratcheted higher a day ahead of a planned rally that protesters have dubbed "Friday of Departure," and presidential guards loyal to Saleh clashed with army units backing opposition groups demanding his ouster.
But a top general who has thrown his weight behind the protesters 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.
Yassin Noman, head of Yemen's opposition coalition, dismissed Saleh's 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.
General Ali Mohsen, who sent troops to protect pro-democracy protesters in Sanaa, said the options before Saleh were now few, and criticized what he described as his "stubbornness," but said the armed forces were committed to protecting protesters.
He said military rule in Arab countries was outdated and that the people would decide who would govern them in the framework of a modern, civilian state.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 Saleh's kinsman 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 offered amnesty to defecting troops in a meeting with senior commanders, calling their decisions foolish acts taken in reaction to violence in Sanaa last Friday, when 52 protesters were shot dead.
Yemen lies on key shipping routes and borders the world's leading oil exporter Saudi Arabia. Al Qaeda has used Yemen as a base to plot attacks in both Saudi Arabia and the United States, and both countries have bet on Saleh to contain the group.
Washington and Riyadh, Yemen's main financial backer, have long seen Saleh as a bulwark against a resurgent Yemen-based al Qaeda network, which has entrenched itself in the mountainous state. U.S. Defense Secretary Robert Gates said Washington had not planned for an era without Saleh.
Western countries and Saudi Arabia are worried about a power vacuum if Saleh goes that could embolden al Qaeda.
Mohsen, an Islamist seen as close to the Islamist opposition, said the army would work with the international community against terrorism.
With no clear successor and conflicts gripping northern and southern Yemen, the country of 23 million faces fears of a breakup, in addition to poverty, a water shortage, dwindling oil reserves and lack of central government control.
Northern Shi'ites have taken up arms against Saleh, and southerners dream of a separate state.
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. Britain said on Wednesday it was temporarily pulling out part of its embassy team from Sanaa ahead of protests expected on Friday.
TIDE IS TURNING
Saleh and opposition groups have both made proposals for reform. On Wednesday, Saleh offered new presidential elections by January 2012 instead of September 2013, when his term ends.
The Wall Street Journal reported that Saleh and Mohsen were hashing out a deal that would involve both men resigning within days in favor of a civilian transitional government. But there was no confirmation from senior officials.
An umbrella group of civil society organizations called for a transitional council of nine figures "not involved with the corruption of the old regime" to draw up a new constitution over a six-month period ahead of elections.
But the issue of what happens to Saleh, who came power in the north in 1978 and oversaw unity with the south in 1990, was left untouched in the proposal from the 'Civil Bloc'.
Opposition parties 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," said spokesman Mohammed al-Sabry.
Saleh made the offer in a letter sent not only to the opposition but also to General Mohsen.
"The political tide in Yemen has turned decisively against President Ali Abdullah Saleh," an International Crisis Group report said. "His choices are limited: he can fight his own military or negotiate a rapid and dignified transfer of power."
Saleh reacted to the loss of his ally Mohsen, seen as Yemen's second most powerful figure, with a series of meetings with military and tribal leaders where he warned against a "coup" that would lead to civil war.
Saleh also has intelligence services on his side and security sources say he has beefed up his personal security for fear of an assassination attempt.
Protesters who have been encamped in their thousands outside Sanaa University for some six weeks have hardened in their attitude toward Saleh, rejecting any idea of his remaining.
They hope the "Day of Departure" after Friday prayers could bring hundreds of thousands onto the streets. Washington, which has urged U.S. citizens to leave Yemen, warned those remaining to stay away from demonstrations on Friday.
Around 10,000 people gathered on Thursday morning, chanting slogans such as "Go, go, you coward; you are an American agent."
Protesters are divided over what they think of Mohsen, an Islamist from the same Hashed tribal confederation as Saleh.
"The country risks replacing the current regime with one bearing striking similarities, dominated by tribal elites from Hashed and powerful Islamists," the ICG report said.
(Additional reporting by Mohamed Sudam and Mohammed Ghobari; Writing by Samia Nakhoul; Editing by Matthew Tostevin)