At least two people were killed and seven others wounded after a bomb planted on a motorcycle exploded outside a mosque in Karachi on Friday, police said.

At least two people were killed and seven others wounded after a bomb planted on a motorcycle exploded outside a mosque in Karachi on Friday, police said.

The blast took place in congested Aram Bagh area of Pakistan's biggest city, outside a mosque.

Pakistan has been hit by a rising wave of sectarian violence in recent years.

A police spokesman said two were killed in the blast and seven wounded.

Saif-ud-Din, a witness, said people were coming out of the mosque after Friday prayers when there was a huge blast and many people fell on the ground.

"I was inside the mosque when the bomb exploded and I saw people falling to the ground," Din told AFP.

Umer Khatab, a senior officer at the police Counter Terrorism Department, told reporters that about two kilogrammes (4.4 pounds) of explosives were used in the bomb, which was detonated with a timer.

"The bomb was planted to target the people coming out of the mosque," Khatab said.

Many worshippers in bloodstained clothes gathered outside the mosque, searching for relatives.

The blast ripped through the shutters of several nearby shops and shattered windows.