The UN's World Food Programme on Wednesday closed distribution centres serving more than two million people in northwest Pakistan over security fears, a spokesman for the agency said. The move affecting the Swat Valley region comes after a suicide bomber attacked a WFP compound in the capital Islamabad, killing five aid workers this month. "We have closed all our food distribution centres in Swabi, Charsadda, Mardan, Swat, Buner, Dir and Bajaur which are the humanitarian hubs for internally displaced people in the region," said Amjad Jamal, a spokesman for WFP in Islamabad. "We are facing problems regarding security, so it was decided last night to close these centres," Jamal told media. The spokesman said the closures were temporary and that the decision would be reviewed later in the week. The food centres had been giving out supplies for those displaced this year by fighting between the army and Taliban around the Swat Valley, which forced around two million people to flee. Although most have since returned home, many remain in need and 2.2 million people received aid in the past month, said Jamal.