Palestinians hoping to raise $2.8 billion to rebuild Gaza at a conference in Egypt on Monday will find the path to reconstruction blocked by political and logistical factors, relief agencies say. Egypt, which called for the gathering soon after Israel halted its Gaza offensive in January, says leaders from some 70 countries will attend including the presidents of France and Italy, and foreign ministers from Britain and the United States. But the Islamist Hamas movement which runs Gaza is not invited. Donors will seek to ensure no money reaches the group, and there is no guarantee that Gaza's borders will be opened to let sufficient supplies flow in. [...] Daly Belgasmi, the regional director of the U.N.'s World Food Programme (WFP), said: "It's quite challenging ... but we are working closely with Israel to coordinate our movement". The United States is expected to pledge more than $900 million at the conference, but Secretary of State Hillary Clinton also stressed that any aid must not benefit Hamas, which the U.S. deems a terrorist organisation.