A former top United Nations official assigned to Afghanistan said Monday that his ex-boss must be fired for long denying the widespread fraud that plagued Afghanistan's last presidential election.

Speaking with CBS News anchor Katie Couric, Peter Galbraith, who was fired for claiming the United Nations helped cover-up the fraudulent votes, said that Afghan President Hamid Karzai was the primary beneficiary of the stolen election.

"I worked for the United Nations," Galbraith said. "And certainly, the United Nations could have done something to prevent the fraud before it took place. I tried to do that. But my boss, Kai Eide, stopped me."

Eide on Sunday admitted that widespread fraud took place amid the crucial vote. He had been defending himself against claims that he did not do enough to guard against fraud and had actually helped cover up instances where election workers intervened on behalf of President Karzai.

"President Karzai said Sunday that 'foreign propaganda' was holding up the process," Couric said. "What do you think he meant by that?"

Galbraith replied: "Well he is continually trying to deflect the blame for the fraud that was committed on his behalf by suggesting that this is just bad news story, that it's a foreign propaganda. When I tried to intervene to preserve the integrity of the electoral process, he complained that I was engaged in foreign interference.

"This, incidentally, in an election that the international community -- and above all, the Americans, had paid $300 million to conduct and in a country where 100,000 troops are fighting on behalf of the Afghan government. So, that this has been a continuing theme on his part. And it should not be taken at all seriously. In fact one should speak firmly to him and say, 'This is unacceptable.'"

Couric asked if, after such a tainted election, Karzai would even be capable of leading the country.

"[If] he emerges from this process as the next president, he will somehow have to persuade the people who did not vote for him that he is the legitimate president," Galbraith said. "And given all the fraud, that's gonna be a tough sell."

Also Monday, Afghan Maulavi Mustafa Barakzai, who was appointed by the country's supreme court to investigate claims of fraud, resigned his post and charged that United Officials had interfered with his work.

"The election has become a major challenge for the Obama administration, which needs to convince a skeptical Congress and American public to continue waging the costly eight-year war to prevent the Taliban-led insurgency from regaining control of Afghanistan," McClatchy Newspapers reported.

If enough fraudulent votes are tossed from the tally, Karzai may be forced into a runoff election agaisnt Abdullah Abdullah, his former foreign minister. Results from an Afghan probe into the vote are expected later this week.

This video is from CBS News, broadcast Sept. 12, 2009.

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