ROME: A suicide attack on WFP offices in Islamabad killed five staff members of the UN agency, the World Food Programme said in a statement on Monday.

"The death of five people working for the WFP has been confirmed after the suicide attack according to local police," the statement said.

Earlier communiques had spoken of three, then four dead.

The fatalities are four Pakistanis and one Iraqi. The WFP did not give their identity.

"All of the victims were humanitarian heroes working on the frontlines of hunger," WFP executive director Josette Sheeran said earlier in a statement from the agency's Rome headquarters.

"This is a tragedy not just for WFP but for the whole humanitarian community and for the hungry," she said.

The bomber struck inside WFP's heavily fortified offices in the heart of the Pakistani capital. At least five people were injured.