(CNN) -- The discovery of millions of extra ballots proves that President Robert Mugabe intends to rig next week's elections in his favor, Zimbabwe's main opposition party said Sunday.



President Robert Mugabe gestures during a pre-election rally in Harare on Saturday.



Tendai Biti, secretary general of the Movement for Democratic Change, said that leaked correspondence from the election commission showed it had asked the company that is printing paper ballots to make 9 million.



However, the African country has an electorate of 5.7 million registered voters, he said.



Also, 600,000 postal paper ballots were requested for soldiers and police officers, Biti said.



Postal ballots are usually requested for civil servants serving abroad, and the total number of soldiers and police in Zimbabwe add up to no more than 50,000, he said.



"Remember, when they stole this election away from us the last time, they stole it with 350,000 votes," Biti said. "Six hundred thousand is double insurance. They cannot win a free and fair election in this country."



The elections are slated for Saturday.



Mugabe survived a hotly contested presidential challenge from MDC leader Morgan Tsvangirai in 2002 amid widespread accusations of vote rigging.



The president's other challenger this time is former Finance Minister Simba Makoni, who recently announced his bid to unseat Mugabe and was promptly booted out of the ruling party.



Last week, New York-based Human Rights Watch raised doubts about the elections, saying it was likely to be "deeply flawed."



"As the elections near, all indications are that once again the people of Zimbabwe will not be able to freely exercise their civil and political rights and vote for the candidates of their choice," the nongovernmental organization said in a 48-page report.



The elections are expected to provide Mugabe with the toughest challenge yet in his nearly 28 years of rule.



The report said the Zimbabwe Electoral Commission was partisan toward the ruling Zimbabwe African National Union-Patriotic Front and had neither the expertise nor the resources to run the elections properly.  Watch Mugabe threaten to expel companies under British rule. »



That report brought derision from a Zimbabwean official.



"What qualifies them to do what they're doing -- policing the world and Africa in particular?" asked Wilbert Gwashavanhu, political consul at Zimbabwe's embassy in Washington.



"Why don't they go to America and oversee how America holds its own elections?" he said. "Come on, give me a break! You can't judge the elections before they are held."



No matter the final outcome of the election, the international community may never find out whether the vote proved to be free and fair. Independent news organizations are banned from Zimbabwe, and there are no credible monitors in place.



Since 1980, the 84-year-old Mugabe has been the country's only ruler. But his odds of winning this time may be handicapped by Zimbabwe's dire economic situation.



The rate of inflation reported in January was 100,000 percent, and food and fuel are in short supply, the Human Rights Watch document said. With more than three in four Zimbabweans unemployed, few could afford such food and fuel anyway.



The country's downward economic spiral began in 2000, when Mugabe sanctioned the violent seizure of commercial farms, turning some of the land over to insiders and cronies.



For his part, Mugabe remains defiant, blaming his country's economic woes on the West. E-mail to a friend



CNN's Saeed Ahmed contributed to this report.
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