More than 40 people were killed and over 70 others were wounded when a female suicide bomber exploded herself outside an office of the World Food Programme (WFP) WFP office in Khar district of Bajaur tribal agency close to the border with Afghanistan on Saturday.
The Tribal Political Administration confirmed that it was a suicide blast, which was conducted by a female.
Security officials said the casualty toll increased to 40 deaths and more than 70 wounded, majority of whom were whisked to hospitals.
The woman set off the explosives amid a large number of people who were gathered outside the WFP bureau to receive food rations, distributed by the international relief agency.
Officials feared further rise in the death toll saying several of the wounded were in critical condition.