By Jibran Ahmad
PESHAWAR, Pakistan (Reuters) - A suicide bombing at a Pakistani religious center killed at least 13 worshippers on Friday, the third major attack to test the new government since the Taliban vowed revenge for a U.S. drone strike that killed its deputy commander.
The spate of violence has shattered a period of relative calm after the May election that returned former prime minister Nawaz Sharif to power, and underscores the challenges he will face in restoring stability in the country torn by militant violence.
More than 60 people have been killed in less than a week from attacks that included suicide bombers targeting women students, a hospital and a funeral procession.
Friday's blast tore through a Shi'ite Muslim seminary in the volatile city of Peshawar, killing at least 13 and injuring 40, police said. Dazed victims in bloodied clothes wandered through rubble and past shattered ornate tiles.
"The bomber was brought by two other persons who shot dead the security guard," police chief Shafiullah Khan said.
It was unclear who carried out the attack. Pakistan has suffered a growing wave of sectarian killings against Shi'ite Muslims, who make up a little over 10 percent of the population.
Security forces blamed the Pakistani Taliban for the suicide bombing and for the funeral attack. The group's spokesman denied any involvement but claimed another killing, the shooting of a provincial lawmaker and his son in the commercial city Karachi.
An allied radical Sunni Islamist group that targets Shi'ite Muslims admitted to the bus and hospital attacks.
Before the election, Sharif suggested he would be willing to negotiate to end four years of war with the Taliban in rugged tribal areas. But the group withdrew an offer of talks after a May 28 drone strike killed its deputy leader, Wali-ur-Rehman.
"There was no formal session of talks with the government but both sides were making a plan when the drone carried out missile strikes," Taliban spokesman Ihsanullah Ihsan told Reuters this week.
The group vowed to teach Pakistan and the United States a lesson for the killing. It believes the Pakistani government cooperates with Washington on drone attacks.
Known as the Tehreek-e-Taliban, the Pakistani Taliban have carried out devastating attacks against the Pakistani military and civilians. It is a separate entity to the Afghan Taliban, though allied with them.
The violence has divided opinion in Pakistan and many in the military are concerned that a political settlement could effectively concede territory to the militants.
Despite the drone strike setback, some level of negotiation seems likely, all the more so since the United States and Afghan Taliban this week announced plans to talk.
(Writing by Frank Jack Daniel, Editing by Michael Roddy)