Talking to BBC, senior police official Tahir Alam who was outside the WFP offices, said the explosion appeared to have been caused by a timed bomb planted in the basement of the offices.  

A female WFP employee talking to APTN said, “I was on the upper floor when there was the sound of a huge explosion downstairs.”

She adde, “I found many of colleagues lying on the floor full of blood. We immediately put the most critically wounded in a vehicle and rushed them to hospital.”

This is said to be the most serious attack in least three months to take place in the city and security has been tightened across Islamabad.

Last week at least 16 people died in two suicide car bomb attacks in north-western Pakistan. It is reported a string of recent bomb attacks show the Taliban appear to be reasserting themselves after a series of setbacks.