Islamabad, Oct 5 (IANS) Three people, including a foreigner, were killed Monday in a suicide bomb blast at the UN World Food Programme office in an upscale locality of this Pakistan capital.

The UN temporarily suspended all its operations. Ishrat Rizvi, national information officer for the United Nations Information Centre in Islamabad, said: "We have temporarily suspended our operations in Pakistan due to the security risks to the UN staff."

The explosion caused a major blaze in the WFP office and thick smoke began to billow out of the building, where about 70 WFP employees were at work.

The explosion shattered windows in the lobby of the compound and left victims lying on the ground in pools of blood.

"There was a huge bang and something hit me. I fell on the floor bleeding," said Adam Motiwala, an information officer at the UN agency who was hospitalised with injuries to his head, leg and ribs.

Tahir Alam Khan, senior superintendent of police, described it as a "well planned blast".

He said the dead included Gul Mukhtar, a receptionist, Farzana Barkat, an assistant at WFP, and Boton Ali, an Iraqi national.

"We are getting the list of employees and visitors to investigate everything properly and relief activities are underway," The News International quoted him as saying.

The WFP office is located at F-8 sector of downtown Islamabad that houses several offices and homes of foreign diplomats. The private house of President Asif Ali Zardari is also located in the F-8 sector, Xinhua said.

Zardari and Prime Minister Yousuf Raza Gilani have strongly condemned the blast at the WFP office in Islamabad and ordered an inquiry.

Islamabad's deputy police chief Bin Yamin said: "We have found parts of a severed head and two legs which indicate that it might be a suicide bombing."

"Initial investigation shows that seven to eight kg of explosives were used in the explosion," DPA quoted him as saying.

Yamin said the attacker, who was between 22 and 26, detonated his explosives in the lobby, killing three people.

The WFP provides food to millions of impoverished Pakistanis and the agency was recently involved in providing relief to about two million people displaced by an army offensive against militants in the Swat valley.

Six people, including two security guards, were being questioned following the blast