A bomb in the northwestern Pakistan city of Peshawar killed 33 people and wounded 70, a week after a bombing at a church in the frontier city killed scores.
The latest blast was outside a police station in Peshawar in an area crowded with shops and families.
Reuters reports there was no immediate claim of responsibility.
Islamist violence has been on the rise in Pakistan in recent months, undermining Prime Minister Nawaz Sharif's efforts to tame the insurgency by launching peace talks with the Taliban.
It follows an attack by a Taliban faction on Peshawar's Anglican church last Sunday that killed more than 80 people, the deadliest attack on Christians in predominantly Muslim Pakistan.
The Taliban have repeatedly rejected Pakistan's constitution and have called for the full implementation of Islamic law and for war with India.
Mr Sharif is due to meet Indian counterpart Manmohan Singh on the sidelines of the United Nations General Assembly later on Sunday, only hours after Mr Singh described Pakistan as the "epicentre of terrorism in our region".