Doctors in Islamabad warned on Wednesday that the death toll from a marketplace bombing could rise.

It was the deadliest attack to hit the Pakistani capital since 2008 and came amid government efforts to negotiate an end to a seven-year insurgency by the Tehreek-e-Taliban Pakistan.

Doctors at Islamabad's Institute of Medical Sciences hospital said some of the wounded were in critical condition. Clinic staff said at least 18 bodies had been received and 50 other people were being treated for wounds.

Hidden in fruit carton

Police said at least five kilograms of explosives hidden in a fruit carton detonated as morning shoppers were buying supplies.

The blast left a 1.5-meter (five-foot) diameter crater at the site.

There was no immediate claim of responsibility.

Wednesday's blast came a little over a month after a gun and suicide bomb attack at a court complex in Islamabad in which 11 people including a judge were killed.

Northwestern Pakistan has been at the center of the Taliban insurgency in recent years but there have been very few attacks in the capital.

ipj/msh (dpa, AP, AFP)