By Cynthia Johnston and Mohammed Ghobari
SANAA (Reuters) - Yemeni protesters demanding the ouster of President Ali Abdullah Saleh said on Tuesday they would insist he leave power soon, blaming him for violence that has raised U.S. fears of chaos that could benefit militants.
Explosions at an arms factory on Monday killed more than 100 people in a southern town where Islamists seemed to have driven out government forces, a reminder of instability that Saleh's Western allies fear in the poorest Arab state.
Al Arabiya TV said the death toll could rise to around 150.
The main coalition of opposition groups said Saleh was to blame for the presence of militant groups including al Qaeda in Abyan province, where the blast took place.
"We condemn this ugly crime and accuse the president and his people of involvement with al Qaeda and armed groups to whom handed over government institutions in Abyan. The chaos was planned in advance," it said in a statement.
"Saleh's continuation in power is a danger to Yemen, its people and international interests," the group added.
Abyan residents said in recent days that security forces had deserted the town of Jaar, scene of the blast. The governors of Jawf and Saada provinces in the north have also left, perhaps fearing confrontations with tribes opposed to the president.
In central Yemen, the governor of Maarib was stabbed after trying to disperse a protest earlier this month.
Saleh, who has been alternately conciliatory and defiant, has vowed in public to make no more concessions to opponents demanding he step down after 32 years of authoritarian rule.
A perennial survivor of civil wars and militancy, he has said Yemen could slide into armed conflict and fragment along regional and tribal lines if he leaves office immediately.
But protesters who have been camped out around Sanaa University since early February also said they found the withdrawal of security and officials in some areas suspicious and accused Saleh of fomenting strife to political reasons.
"Saleh wants to scare us and the world with chaos, which he has started causing in some areas," said Ali Abdelghani, 31, a civil servant among thousands of protesters in Sanaa.
"But we are capable of exposing this game. There are popular committees in all provinces to bring security as the president has removed security in some places for chaos to spread."
Dozens of policemen and soldiers from different units joined the protests on Tuesday, milling around and chanting slogans such as "The people want the fall of the regime" and "The police and army are partners in providing daily needs."
"We are optimistic about the success of our revolution. It is just a question of time," said Marwan Hussein, 18, a student.
SALEH THE BULWARK
Washington and neighboring U.S. ally Saudi Arabia have long seen Saleh as a strongman to keep al Qaeda from extending its foothold in a country many see as close to disintegration.
Yemen's al Qaeda wing claimed responsibility for a foiled attempt in late 2009 to blow up an airliner bound for Detroit, and for U.S.-bound cargo bombs sent in October 2010.
Direct talks to broker a transition from Saleh to his opponents appeared to have stalled in a public game of brinkmanship. His ruling General People's Congress party has recommended forming a new government to draft a constitution ahead of early parliamentary and presidential elections.
"Those who are hungry for power ... they should turn to elections instead of chaos, and they will get to power if they have the trust of the people," Saleh told supporters on Monday.
An opposition spokesman said that talks had been halted but another figure, speaking on condition of anonymity, said a deal was still possible and that Saleh was looking to ease conditions the opposition wanted to set on his family's future activities.
"We are on the path to completing a deal," the opposition figure said on Monday. "The president is trying to improve the negotiating conditions, especially relating to the situation of his sons and relatives."
The deal, if reached, probably would involve the resignation of Saleh and General Ali Mohsen, a kinsman and former ally who defected then sent troops to protect the protesters.
The sons and close relatives of the president also would leave their positions in a deal, but Saleh's side wants guarantees they would not be pursued legally. It was not clear if they would stay in Yemen, but that was an option.
An opposition source said Saleh was likely to hand over to a vice-president, in line with the constitution. An opposition official said the current vice-president did not want the job and a new figure would probably be chosen.
A new government would be formed to amend the constitution and draft laws for parliamentary and presidential elections, political sources said.
However, as in Egypt, where the overthrow of Hosni Mubarak last month after 30 years in power was an inspiration to Saleh's opponents, the focus would be on amendments to the current basic law, rather than on drafting a new constitution from scratch.
The transition was likely to proceed faster than Saleh said last week he was ready to offer -- power could be transferred well before the end-of-the-year deadline Saleh proposed. There has been talk of switching to a parliamentary system based on proportional representation, political sources said.
(Writing by Andrew Hammond; Editing by Michael Roddy)