* Death toll from series of bombings rises to 126
* Sunni group claims responsibility for deadliest attack
* Human Rights Watch says authorities are failing Shi'ites
By Gul Yousufzai
QUETTA, Pakistan, Jan 11 (Reuters) - In a rare challenge, a Shi'ite Muslim leader publicly criticised Pakistani military chief General Ashfaq Kayani over security in the country on Friday after bombings targeting the minority sect killed 93 people.
The criticism of Kayani, arguably the most powerful man in the South Asian state, highlighted Shi'ite frustrations with Pakistan's failure to contain Sunni Muslim militant groups who have vowed to wipe out Shi'ites.
"I ask the army chief: what have you done with these extra three years you got (in office)? What did you give us except more death?" Maulana Amin Shaheedi, who heads a national council of Shi'ite organisations, told a news conference.
Most of Thursday's deaths were caused by twin attacks aimed Shi'ites in the southwestern city of Quetta, near the Afghan border, where members of the minority group have long accused the state of turning a blind eye to Sunni death squads.
Shi'ite leaders were so outraged at the latest bloodshed that they called for the military to take control of Quetta to shield them and said they would not allow the 93 victims of twin bomb attacks to be buried until their demands were met.
The burials had been scheduled to take place after Friday prayers but the bodies would remain unburied until Shi'ites had received promises of protection, they said.
"They will not be buried until the army comes into Quetta," Shaheedi said.
Akbar Durrani, home secretary of Baluchistan province, of which Quetta is the capital Durrani said scores of bodies had been brought out into the road by the bomb site as a protest.
About 2,000 ethnic Hazara Shi'ites were sitting at the site of the attack with the shrouded bodies of those killed in the attacks, demanding that the army replaces the provincial government, he said.
Islamic tradition requires the dead to be buried as soon as possible, so leaving loved ones unburied is a powerful sign of grief and rage.
Violence against Pakistani Shi'ites is rising and some communities are living in a state of siege, a human rights group said on Friday.
"Last year was the bloodiest year for Shias in living memory," said Ali Dayan Hasan of Human Rights Watch. "More than 400 were killed and if yesterday's attack is any indication, it's just going to get worse."
A suicide bomber first targeted a snooker club in Quetta. A car bomb blew up nearby 10 minutes later after police and rescuers had arrived.
In all, 93 people were killed in the twin blasts and 121 wounded. Nine police and 20 rescue workers were among the dead.
"It was like doomsday. Bodies were lying everywhere," said police officer Mir Zubair Mehmood.
The banned Sunni group Lashkar-e-Jangvi (LeJ) claimed responsibility for the attack in what is a predominantly Shi'ite neighbourhood where the residents are Hazaras, Shi'ites who first migrated from Afghanistan in the 19th century.
While U.S. intelligence agencies have focused on al Qaeda and the Taliban, Pakistani intelligence officials say LeJ is emerging as a graver threat to Pakistan, a nuclear-armed, strategic ally of the United States.
It has stepped up attacks against Shi'ites across the country but has zeroed in on members of the sect who live in resource-rich Baluchistan.
The paramilitary Frontier Corps is largely responsible for security in Baluchistan province but Shi'ites say it is unable or unwilling to protect them from the LeJ.
"STATE OF SIEGE"
The LeJ wants to impose a Sunni theocracy by stoking Sunni-Shi'ite violence. It bombs religious processions and shoots civilians in the type of attacks that pushed countries such as Iraq towards civil war.
The latest attacks prompted an outpouring of grief, rage and fear among Shi'ites, many of whom have concluded that the state has left them at the mercy of the LeJ and other extremist groups who believe they are non-Muslims.
"The LeJ operates under one front or the other, and its activists go around openly shouting 'infidel, infidel, Shi'ite infidel' and 'death to Shi'ites' in the streets of Quetta and outside our mosques," said Syed Dawwod Agha, a top official with the Baluchistan Shi'ite Conference.
"We have become a community of grave diggers. We are so used to death now that we always have shrouds ready."
The roughly 500,000-strong Hazara people in Quetta, who speak a Persian dialect, have distinct features and are an easy target, said Dayan of Human Rights Watch.
"They live in a state of siege. Stepping out of the ghetto means risking death," said Dayan. "Everyone has failed them: the security services, the government, the judiciary."
Earlier on Thursday, a separate bomb killed 11 people in Quetta's main market.
The United Baloch Army claimed responsibility for that blast. The group is one of several fighting for independence for Baluchistan, an arid, impoverished region with substantial gas, copper and gold reserves.
Baluchistan constitutes just less than half of Pakistan's territory and is home to about 8 million of the total population of 180 million.
In another attack on Thursday, in Mingora, the largest city in the Swat valley in the northwest, at least 22 people were killed when an explosion targeted a public gathering of residents who had come to listen to a religious leader.
No one claimed responsibility for that bombing. Swat has been under army rule since a military offensive ejected Pakistani Taliban militants in 2009.
The LeJ has had historically close ties to elements in the security forces, who see the group as an ally in any potential war with neighbouring India. Security forces deny such links.
In a measure of the outrage, several Pakistani social media users posted Facebook comments urging the U.S. to expand its covert programme of drone warfare beyond Taliban strongholds on the Afghan border to target LeJ leaders in Baluchistan.
Among the dead in Quetta was Khudi Ali, a young activist who often wore a T-shirt with fake bloodstains during protests against the rising violence against Shi'ites.
Ali's Twitter profile said: "I am born to fight for human rights and peace."