Power vacuum looms for Afghanistan as UN delays date for result of presidential elections to mid-September despite Karzai's plans to leave office next week.Afghanistan faced the prospect of a constitutional power vacuum after Hamid Karzai, its president since 2002, warned that he would step down imminently despite a deadlock over his successor. Mr Karzai said his bags were packed and he was determined to quit office as he presses for his successor to be sworn in on Tuesday. However the UN delegation in Kabul has said it will not declare the results of an audit of voting until September 10. The announcement came hours after David Cameron demanded a power-sharing government to preserve the gains made in Afghanistan since the deployment of Nato troops during phone calls with Ashraf Ghani and Abdullah Abdullah, the rival candidates. Mr Karzai has already taken over another house in the city and is already overseeing the transfer of his personal possessions. "The president has packed up already, days ago," Aimal Faizi, Mr Karzai's spokesman said. "A lot of the furniture is staying as it belongs to the palace, but his personal belongings, everything and especially his books, which are very dear to him, are packed. He has a good collection of books, all kind of new and very old historic books - that is already put in cartons and they are all ready to leave the palace, but they haven't gone to the next place yet." Jan Kubis, the UN representative in Afghanistan said "not possible" to finish an audit of a disputed election by September 2, Mr Karzai's office said. The UN is supervising the audit of votes from a run-off ballot between the two candidates, Mr Abdullah and Mr Ghani. They have both claimed victory in the election intended to mark the country's first democratic transfer of power. The deadline was abandoned despite a Nato summit in Britain next Thrursday and Friday that will consider future support for Afghanistan after the 13-year US-led combat mission ends this year. Nato wanted a new president should be in place before the summit to prove that the country has becoming a functioning state after receiving billions of dollars of military and civilian aid assistance. Mr Abdullah has formally withdrawn his backing for the review of all ballots that had been set up to resolve the stalemate over who won the June 14 election. Preliminary results suggested Mr Abdullah lost by a million votes to Mr Ghani, triggering accusations of massive electoral fraud. Following Mr Cameron's calls, a Downing Street spokeswoman said: "He emphasised the enormous prize at stake for the Afghan people - to secure their democratic future - and that he hoped that the process could be completed by the Nato summit. "The Prime Minister said that the summit represented an opportunity to reflect on the progress made in Afghanistan over the last 10 years and to look at how Nato allies could work with the new government to support Afghanistan in the future. Mr Karzai, 56, who lives in the palace with his wife Zinat and their three children, is banned from standing for a third term in office and he often said that he is looking forward to retirement and to becoming a "citizen of Afghanistan" who is ready to help his successor if asked. The withdrawal undermined a US-brokered deal in which both candidates agreed to accept the audit and for the winner to then form a national unity government. Negotiations over the unity government have also struggled, while officials deny reports that some current ministers planned to break the impasse by setting up a "interim administration" to take power.