Afghan President Hamid Karzai said on Thursday that a probe into possible voting irregularities during the August 20 presidential election should continue, but downplayed the allegations by saying that fraud “happens all over the world”.

In his first press conference since last month’s ballot, Karzai said he “firmly” believed in the vote’s integrity but that an investigation into fraud allegations should continue.

Robert Parsons discusses the disputed Afghan election results

“I believe firmly, firmly in the integrity of the election and the integrity of the Afghan people, and the integrity of the government in that process,” he told reporters gathered at the presidential palace in the Afghan capital, Kabul.

"If there was fraud, it was small -- it happens all over the world," he added.

Full preliminary results from the election released on Wednesday gave Karzai 54.6 percent of the vote, putting him over the 50-percent threshold to avoid a run-off. But just hours before the figures were released, EU election observers announced that almost a quarter of the votes – 1.5 million of the 5.6 million votes cast – could turn out to be fraudulent, with 1.1 million of the suspicious ballots going to Karzai.

“Massive fraud was taking place at polling station level and when all these ballot boxes arrived at the tally centres, instead of being quarantined and investigated, they were accepted as good results,” said Dimitra Ioannou of the EU electoral monitoring mission.

A statement from Karzai’s campaign office lashed out at the EU’s assessment, calling it "partial” and “irresponsible”.

Karzai's 1.1 million questionable votes could become a real headache, according to FRANCE 24's Jerome Starkey in Kabul. "If those votes were excluded, [the president's] lead would be slashed from 54[.6] to just 46 percent," Starkey says, thus triggering a run-off with Karzai's closest challenger, Abdullah Abdullah.

Despite pledging his faith in the integrity of the vote, Karzai said he supports an examination into any irregularities. "If there is fraud, it has to be investigated, but investigated fairly and without prejudice," Karzai said in his remarks on Thursday.

But the Karzai camp made clear that it expects Afghan authorities to lead the investigation.

"According to the constitution of Afghanistan, addressing the electoral complaints is the responsibility of the Election Complaints Commission (ECC)," a Karzai campaign statement said.

In his address to reporters, Karzai backed this view. "I hope our foreign friends respect the people of Afghanistan and let the IEC (Independent Election Commission) and the ECC fulfill their work without interference," he added.

The Afghan ECC, under the auspices of the United Nations, says it is recounting votes cast at 10% of all the polling stations. More than 200,000 votes have already been disqualified from the official results.