By Cynthia Johnston and Mohammed Ghobari
SANAA (Reuters) - Yemeni protesters demanding an end to President Ali Abdullah Saleh's rule 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 the instability that Saleh's Western allies fear in the poorest Arab state.
Al Arabiya TV said the death toll could rise to about 150.
The main coalition of opposition groups said Saleh was to blame for the presence of militants, 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 government institutions have been handed over 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 for 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.
On Monday, Saleh's son-in-law Yahya Mohammed Ismail joined the protesters, addressing them in a speech shown on Al Jazeera television.
SALEH THE BULWARK
Washington and neighbouring 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.
U.S. officials have said openly they like working with Saleh -- who has allowed unpopular U.S. military operations in Yemen against al Qaeda -- and Saleh has said the U.S. ambassador was involved in talks to find a solution.
Indirect talks to broker a transition from Saleh to his opponents restarted on Tuesday after direct talks broke down in recent days, a source close to the talks said.
"They want to agree a framework now and details will be worked out in direct talks," he said.
Saleh's ruling General People's Congress party has proposed a new government to activate Saleh's offer of a new constitution ahead of early parliamentary and presidential elections.
"Those who are hungry for power ... they should turn to elections instead of chaos. They will get to power if they have the trust of the people," Saleh told supporters on Monday.
The opposition say they believe Saleh is maneuvering to avoid limits on his family's future activities and a guarantee they would not face legal action over corruption.
"We are on the path to completing a deal," an 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 last week.
Opposition figures say Saleh could hand over to a new vice-president, in line with the constitution.
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 the end-of-year deadline Saleh has proposed.
(Writing by Andrew Hammond; Editing by Janet Lawrence)