Two bomb attacks in the Pakistani cities of Lahore and Karachi killed at least 11 people on Tuesday and left more than 50 people wounded, officials said.
A teenage suicide bomber in Lahore blew himself up near a Shiite Muslim procession, killing at least nine people and wounding more than 50, in an attack claimed by Taliban militants who said they had targeted police.
About 90 minutes later a motorcycle bomb detonated in the southern city of Karachi, killing two people, including a policeman, police and hospital officials said.
A doctor at Lahore city's main Mayo Hospital, said the dead included at least three police officials and one woman.
"We have received nine bodies so far," said Zahid Pervez.
There were 52 people wounded, 20 of them critically, including women and children, he added.
"It was suicide attack," said senior police official Rana Faisal.
"The bomber came close to our checkpoint, threw a bag near a car and blew himself up when policemen tried to stop him."
The bombing took place at a busy intersection in downtown Lahore.
Television footage showed policemen and ambulance workers carrying the wounded away with their hands and on stretchers, while other officers tried to calm the shocked and confused crowd.
Another senior police official, Rao Sardar, said police had tried to apprehend the boy before he blew himself up.
"The policeman stopped this boy and wanted to body search him," he said, adding that he was a teenager.
The suicide attack took place near a religious procession by the Shiite Muslim community to mark the 40th day of mourning of the death of the Prophet Mohammad's grand son Imam Hussain.
An hour and a half later a second bomb explosion in troubled Karachi city, a teeming coastal metropolis where sectarian and political violence is rife, killed two people and injured four others.
"Two bodies have been brought to the hospital, one of the dead is a policeman, the other is still being identified. There are four injured brought here. One is a policeman," said the deputy chief of Karachi's main Jinnah Hospital, Semeen Jamali.
City police chief Fayyaz Leghari said it was a motorcycle bomb but could not yet confirm the target.
"When the bomb exploded it was huge and heard far away... we are still collecting details about the blast and wounded," he said.
The Pakistani Taliban claimed responsibility for the Lahore attack which they said was aimed at security officials in revenge for military operations and US drone attacks targeting militants in their northwest stronghold.
"We claim responsibility for the suicide attack on police in Lahore," said Azam Tariq, spokesman for militant umbrella group Tehreek-e-Taliban Pakistan (TTP), in a telephone call to AFP in Miranshah, the main town in restive North Waziristan tribal district bordering Afghanistan.
"We regret the loss of civilian lives in the attack and warn people to keep away from security forces and government property," he said.
"The attack was in retaliation for drone strikes and military operations in tribal areas. We have more than 3,000 trained suicide bombers," he added.
A city of eight million near the border with India, Lahore has been increasingly subject to Taliban and Al-Qaeda-linked attacks in a nationwide bombing campaign that has killed more than 4,000 people in three-and-a-half years.
Sunni Muslim militant groups have frequently targeted Pakistan's Shiite minority.
Triple suicide bombings at a Shiite mourning procession killed at least 31 people and wounded 280 others in Lahore in early September.
Pakistan tacitly cooperates with the US drone bombing campaign, which Washington does not openly acknowledge, but which US officials say has severely weakened Al-Qaeda's leadership.
Prime Minister Yousuf Raza Gilani "strongly condemned" the suicide attack and ordered an immediate inquiry to investigate the attack, a statement said.