ISLAMABAD (Reuters) -- A suspected suicide bomber has attacked an office of the UN World Food Program (WFP) in the Pakistani capital, Islamabad, killing three staff and wounding several, police and the agency said.
Pakistan is battling Islamist militants who have set off numerous bombs in towns and cities aimed at the security forces and government and foreign targets.
"I went to my office on the first floor and as I sat on my chair there was a huge blast," WFP official Arshad Jadoon told Reuters outside the tightly guarded office in a residential area of the city.
"All of a sudden, a smoke cloud enveloped the building and we came out where wounded people were lying," Jadoon said.
Senior city police official Bin Yameen said one of the dead was an Iraqi national and the other two were Pakistani women. Five Pakistanis were wounded, he said.
A severed head and two legs had been discovered, suggesting the attack was launched by a suicide bomber, Yameen said. Suicide bombers often strap explosives to their torsos, which are obliterated in the blast.
The WFP provides food to millions of impoverished Pakistanis.
The agency was recently involved in providing relief to about 2 million people displaced by an army offensive against militants in the Swat Valley, northwest of the capital.
"This is a terrible tragedy for WFP, and for the whole humanitarian community in Pakistan," said WFP Deputy Executive Director Amir Abdulla, speaking from the agency's headquarters in Rome.
Two of the wounded were in critical condition, the agency said.
Two foreign UN workers were killed in a suicide car-bomb attack on a hotel in the northwestern city of Peshawar in June.
There was no claim of responsibility for the latest attack on the WFP office, which is several hundreds meters from the Islamabad home of President Asif Ali Zardari.
Zardari moved into the official presidential residence soon after his election last year for security reasons.
The army has made significant progress against militants in the Swat Valley and elsewhere in the northwest, and Interior Minister Rehman Malik says the back of the Pakistani Taliban has been broken.
But the militants have struck back with several bomb attacks in recent days as the army prepares to launch an offensive on the Pakistani Taliban's main bastion in the South Waziristan region on the Afghan border.