ISLAMABAD: The United Nations has temporarily closed all its offices across Pakistan after a suicide blast Monday killed four people at the World Food Programme compound in central Islamabad, a UN spokeswoman said.

‘All UN offices in Pakistan have been closed until further notice,’ spokeswoman Susan Manuel told AFP.

Another UN spokeswoman, Ishrat Rizvi, told AFP that the offices would be shut ‘for security reasons.’

A suicide bomber walked into the WFP's heavily fortified offices in Islamabad early Monday afternoon, police say, with three Pakistanis and one Iraqi man killed in the blast.

WFP Deputy Executive Director Amir Abdulla said in a statement from the agency's Rome headquarters that the blast was ‘a terrible tragedy.’

It is the second time the UN community in Pakistan has been hit this year, with two employees from the refugee agency UNHCR and children's agency Unicef killed in the June suicide bombing at a luxury hotel in northwest Peshawar.