KABUL - The United Nations special representative to Afghanistan, Kai Eide, said Sunday that the level of fraud in Afghanistan's presidential election was "significant."

"It is true that in a number of polling stations in the south and the southeast there was significant fraud, but not only there," Eide told reporters.

"The extent of that fraud is now being determined," he said.

Eide called a media conference to answer accusations that he tried to conceal information about the extent of the fraud in the elections, which were held on August 20.

The elections, the results of which are not yet known, have been overshadowed by allegations of widespread fraud, mostly aimed at President Hamid Karzai.

Karzai leads preliminary results with about 55 percent of the vote, against his nearest rival Abdullah Abdullah, who is on 28 percent.

Final results are expected to be announced by the end of this week.

Eide addressed accusations made by his former deputy, Peter Galbraith, who was dismissed last month after a row with his boss over how to deal with the fraud allegations.

Eide was flanked by the ambassadors to Kabul from the United States, Britain and France, with the German ambassador, the European Union's special representative to Afghanistan, and a NATO representative also in attendance.

Visibily angry, Eide said: "Some of these allegations were based on private conversation whilst he (Galbraith) was a guest in my house.

"My view is that private conversations around a dinner table in my house remain just that, private," he said.

The publicity surrounding Galbraith's dismissal, and the accusations he made against Eide "have not only been personal attacks against me and my personal integrity but have affected the whole election process," he said.

Galbraith was sacked on September 30 by UN chief Ban Ki-Moon and immediately went on the offensive, saying the decision sent a "terrible signal" about the UN's commitment to a fraud-free Afghan election.

Differences between the two men began before the poll when Galbraith wanted to eliminate "ghost" polling centres that posed a risk of fraud as they were too insecure to open on election day.

When fraud evidence became "very extensive," he said -- citing high vote numbers from regions where turnout was known to be low -- Eide would not allow the information to be disseminated even to ambassadors based in Kabul.

He also said that 30 percent of Karzai's votes were fraudulent, echoing findings by EU elections monitors that about 1.5 million votes in total -- and 1.1 million for Karzai -- were suspicious.

Eide said it was impossible to know the proportion of fraudulent votes as investigations by the Independent Election Commission and the Electoral Complaints Commission were ongoing.

He denied any suggestion that he had interfered with the process to conceal the level of fraud, saying the UN mandate in Afghanistan "is to support the process not influence the outcome."