Police said a bomb exploded in southern Pakistan, killing at least four people and wounding 25.

Senior police officer Abdul Khaliq Sheikh said the attack took place on Friday in the neighbourhood of Clifton in Karachi.

No one claimed responsibility, but the attack took place a day after a bomb targeting prominent police officer Shafiq Tanoli exploded in another area of Karachi, killing the officer and three others.

The slain officer, who had survived several attempts on his life, was targeted for his active campaigning against terrorists.