By Cynthia Johnston and Mohamed Sudam
SANAA (Reuters) - Yemen opposition groups called on protesters to march on President Ali Abdullah Saleh's Sanaa palace on Friday to force him out, hoping to end a crisis his allies abroad fear will benefit Islamic militants.
"Friday will be the 'Friday of the March Forward', with hundreds of thousands of people...We will arrive where you are and we will remove you," opposition spokesman Mohamed Qahtan told Al Jazeera on Wednesday, addressing the Yemeni leader.
Seven weeks of street protests against Saleh's 32-year rule of the impoverished Arabian Peninsula state has raised alarm in Western capitals at the prospect of a country where al Qaeda has entrenched itself falling apart.
Yemen borders the world's biggest oil exporter, Saudi Arabia, and major shipping routes. Al Qaeda cells in Yemen have in the past two years attempted attacks outside Yemeni soil in Saudi Arabia and the United States.
A succession to Saleh is unclear and the country faces the danger of fragmentation.
Defections including generals, tribal leaders, diplomats and ministers, gained momentum after gunmen loyal to Saleh opened fire on protesters on Friday, causing the deaths of 52 people.
Saleh sacked his cabinet and declared a state of emergency -- which parliament rubber stamped on Wednesday for a 30-day period -- but the bloodshed has lent protests a new severity.
One Wednesday, protesters carried placards saying "No to emergency rule, you butcher!" Some had begun selling T-shirts saying "I am a future martyr."
"As sure as the sun is in the sky, he will go," said Suleiman Abdullah, 28.
Complaining of neglect, southerners have said they want to secede and northern Shi'ites have staged several rebellions against the perennial survivor, now in the biggest fight of his political life.
Long backed by Arab and Western countries as the strongman holding the fractious tribal country together, Saleh is raising the specter of civil war and disintegration if he is forced out in what he says would be a coup.
Defections among the ruling elite have reached senior military commanders, including General Ali Mohsen, commander of the northwest military zone and Saleh's kinsman from the powerful al-Ahmar clan.
"They call for the regime going and that means chaos and destruction. Yes, the regime could go, but via democratic means and that involves the ballot box and elections. Coups are rejected," Saleh told a meeting of tribal figures on Wednesday.
Political analyst Abdul-Ghani al-Iryani said he thought Saleh realized his time was up.
"I think he is just maneuvering for favorable exit terms. Still, with tanks facing off in the streets of Sanaa, he is holding the city hostage," he said. Iryani said Saleh would be seeking immunity from prosecution and protection of assets.
More soldiers were milling around on Wednesday among the thousands of protesters who have been camped in the streets near Sanaa University since early February.
Some were wearing red roses to demonstrate support for what is being termed the "youth revolution." "We are its protection," said one soldier, with a plastic rose affixed to his rifle.
TENSION IN MILITARY
Tension among rival military forces has led to violence.
Presidential guards -- a force commanded by Saleh's son Ahmed -- surrounded an air force battalion in the coastal city of Hudaida after its commander said he supported the protesters.
A presidential guard and a soldier died in clashes between the two forces in the southern coastal city of Mukalla late on Monday, medical sources said.
But protesters are divided over what they think of Ali Mohsen, an Islamist who was commonly regarded as the second most powerful man in the country before he decided to defect.
Some protesters have displayed his picture on their tents but the opposition regard his motives with suspicion and would not want him to have a role in any future transitional government.
Followers of the Houthi movement of Zaidi Shi'ites in the north said he was responsible for the army's conduct during rebellions of recent years.
"We see Ali Mohsen's joining us as a corruption of the revolution. The revolution is not against an individual but against a system," said Abdullah Hussein al-Dailami, 33, from Saada in the north. He said Mohsen had been Saleh's accomplice.
The United States, grappling with the diplomatic fallout of uprisings and uncertainty across the Arab world, has voiced rare public alarm about the situation in Yemen and the possible fall of someone seen as an ally in the fight against al Qaeda.
An aide to Saleh said he would leave office only after organizing parliamentary polls and establishing democratic institutions, by January 2012 -- a declaration the opposition promptly rejected. Saleh has already said he will not run when his term ends in 2013, an early verbal concession also rejected.
The standoff is taking its toll on Yemen's fragile economy.
Liquefied natural gas producer Yemen LNG has told customers that unrest could lead to supply disruptions, leading stakeholder Total said.
Opponents complain that Yemen under Saleh has failed to meet the basic needs of the country's 23 million people. Unemployment is around 35 percent and 50 percent for young people. Oil wealth is dwindling and water is running out.
(Additional reporting by Khaled Abdullah, Mohammed Ghobari, Alistair Lyon, Andrew Hammond; Writing by Andrew Hammond; Editing by Ralph Boulton and Samia Nakhoul)