The inability of the Palestinian Authority and Hamas to cooperate in the Gaza Strip has hit vital post-war rebuilding and international donors are wary of sending more funds, a senior United Nations envoy said on Thursday.The main UN aid agency in the coastal enclave said on Tuesday it was suspending payments to tens of thousands of Palestinians for repairs to homes damaged in the July-August war with Israel because money from international donors had run out."We need a government ... that is able to take responsibility," Robert Serry, the UN Special Coordinator for the Middle East Peace Process and the Secretary General's personal envoy to the Palestinians, told Reuters.He said a stable, functioning administration in the Gaza Strip was vital for donor countries to have confidence that their money would be used effectively. But donors, for their part, had provided far too little funding, he said."We have a (UN) mechanism that is working but almost everything else is not in place and that influences decisions of donors ... (but) I am not (absolving) donors for their responsibilities, the fact that so little money is available is scandalous," he added.On Wednesday, dozens of furious Gazans stormed Serry's compound in the enclave after the UN agency declared it had run out of money. Serry, who was not present, withdrew UN monitors from the Gaza Strip.He said their removal was temporary but added that the outlook for Gaza would only turn positive if the Western-backed Palestinian Authority and Islamist Hamas resolved their differences. An Egyptian-brokered reconciliation deal has failed to take effect with Hamas remaining the dominant force in the Gaza Strip."These two different strands of administration need to be restructured. You need one affordable civil servants' apparatus in Gaza and as long as no steps are being taken in that direction and if that is not resolved ... we will keep discussing Gaza for a long time and in a very negative way."Little of the total $5.4 billion pledged for Gaza's reconstruction at a Cairo conference of international donors last October has reached the territory, and thousands of Palestinians have been sheltering in tents near destroyed homes.Thousands more have been living in damaged buildings, using plastic sheeting to try to keep out the rain. Around 20,000 displaced are still being housed in UN-run schools.Hamas and other factions have warned that fighting with Israel could resume unless rebuilding is stepped up. The Palestinian Authority, led by President Mahmoud Abbas, was meant to oversee rebuilding because Israel and the West fear Hamas could use the materials to build tunnels and fortifications.