CHAKWAL, Pakistan (Reuters) - A suicide bomber blew himself up at a gathering of minority Shi'ite Muslims in Pakistan on Sunday killing 22 people a day after a deadly suicide attack in the capital, police said.
Pakistan is crucial to U.S. efforts to stabilize neighboring Afghanistan and U.S. President Barack Obama has said the release of additional U.S. aid to the nuclear-armed country depends on how it tackles terrorism.
The attack in the central city of Chakwal came a day after a pilotless U.S. drone aircraft killed 13 people including militants in the northwest and a suicide bomber killed eight soldiers in Islamabad.
About 2,000 people had gathered at a Shi'ite religious center in Chakwal, about 100 km (60 miles) south of Islamabad, for a ceremony when the bomber struck.
"There was a break in the ceremony and some people were going out and others were coming in when all of a sudden a young man tried to run into the crowd," said witness Amjad Hussain.
"When guards tried to stop him at the gate he blew himself up."
Regional police chief Nasir Khan Durrani said 22 people had been killed and 35 wounded. Durrani said the death toll would have been much higher if the bomber had managed to force his way into the crowd.
Surging militant violence has raised fears for nuclear-armed Pakistan's prospects, a year after a civilian government came to power ending eight years of military rule.
President Asif Ali Zardari, the widower of assassinated former prime minister Benazir Bhutto, and the coalition government are also struggling to revive an economy propped up by a $7.6 billion International Monetary Fund loan.
Outside the religious center, blood was splattered over the gate and walls while shoes and other possessions were strewn on the ground. Three mangled motorcycles lay outside the gate.
Pakistan has a long history of tit-for-tat attacks by militants from the majority Sunni and minority Shi'ite Muslim communities.
But sectarian militancy intensified after some anti-Shi'ite groups forged ties with al Qaeda and Taliban militants, security officials say.
Shi'ites account about 15 percent of Pakistan's 170 million mostly Sunni population and in general the two communities live in peace.