KABUL  - Afghanistan will not have a new president in time for a key NATO summit next week, officials said Thursday, as the country's prolonged election crisis lurched towards another damaging delay.

The latest deadline of September 2 was abandoned as a UN-supervised audit of all eight million votes has fallen behind schedule, with both candidates still claiming victory in the fraud-tainted vote.

A NATO summit in Britain from September 4-5 is meant to agree on future support for Afghanistan after the 13-year US-led combat mission ends this year.

Meanwhile, outgoing Afghan President Hamid Karzai has packed up all his personal possessions and is ready to leave the palace, his spokesman said Thursday, even though the disputed election has failed to find his successor.

Karzai, who has lived in the former royal palace in central Kabul since 2002, has supervised the removal of his precious library of books from shelves inside his heavily-fortified residence.

He is due to move into another house in the city, though it is unclear how active he will be in politics after ruling Afghanistan for 13 turbulent years since the fall of the Taliban regime. "The president has packed up already, days ago," Karzai's spokesman Aimal Faizi told AFP. "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."

Ashraf Ghani and Abdullah Abdullah, the two candidates vying to succeed Karzai, are stuck in a prolonged stalemate over who won the June 14 election, which has been engulfed in allegations of massive fraud.

Karzai, 56, has lived in the vast palace complex behind multiple layers of rigorous security with his wife Zinat and their three children, the youngest of whom was born earlier this year.

Due to the threat of assassination, he has been unable to travel freely around the country and has instead hosted an almost constant series of meetings with Afghans ranging from feared warlords to ordinary villagers.

Under the constitution, he 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.

Karzai, who has publicly stayed neutral during the election, has pushed for the inauguration to be held next Tuesday - even though Ghani and Abdullah both still claim to have won.

Faizi said the inauguration would be a "domestic" event without foreign dignitaries due to uncertainty over the schedule.

"The preparations are underway and the list of invitees is already prepared and we have shared the list with the two candidates... if they want to add names," he said.

"The president is doing his best to have a responsible conclusion of the election process before the end of this month, so we can have an inauguration right after the president-elect is declared."

But the political crisis has only deepened in recent days, with Abdullah pulling out a UN-supervised audit of all eight million votes.

Abdullah, who came far behind Ghani in preliminary results from the June run-off, accused the audit of failing to clean out fraudulent votes.

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.

The UN has voiced fears that the impasse could trigger a spiral of instability and revive ethnic divisions as US-led NATO combat troops head home and Taliban insurgents seek to exploit months of political paralysis.