Updated

Uganda's longtime president has won another term, the country's election commission said Sunday, but the top opposition leader alleged the election was fraudulent and vowed to reject the results.

The electoral commission said Sunday that President Yoweri Museveni won 68 percent of votes in Friday's poll, allowing him to extend his 25-year hold on power. The commission said challenger Kizza Besigye took 26 percent of the vote.

Electoral Commission chairman Badru Kiggundu said 59 percent of voters in the East African nation participated.

Besigye has previously threatened Egypt-style protests if the results are not in line with what he and his supporters believe the true returns are.

As the announcement approached Sunday, Besigye pledged to work "to bring an end to the illegitimate government".

But he stopped short of calling for street protests on Sunday, saying he was still considering his options. Museveni said last week he would jail anyone who tried to spark Egypt-style unrest.

Besigye said widespread bribery, ballot-stuffing and harassment rendered the poll illegitimate.

"(We) reject the outcome of the elections," Besigye said Sunday. "(We) reject the leadership of Mr. Yoweri Museveni."

Foreign election observers said that there had been serious flaws with the voting process and the campaign. They said state resources were used to skew the elections in Museveni's favor.

"The power of incumbency was exercised to such an extent as to compromise severely the level playing field between the competing candidates," said Edward Scicluna, head of the European Union monitoring mission.

Amama Mbabazi, secretary general of Museveni's ruling National Resistance Movement, called the results "a great victory" and urged Besigye to accept the outcome.

"It is dishonest of his part to reject the results of a process that he has participated in fully," Mbabazi said.

Election chief Kiggundu rejected opposition claims that officials systematically rigged the results, and called on Besigye to provide evidence.

"I want him to prove it," Kiggundu said. "It is their constitutional right to make their observations."

Museveni, an ex-rebel commander who seized power at the head of a guerrilla army in 1986, once criticized African rulers who clung to power. But he sought another five-year term as a president who has fostered peace, stability and growth.

While previous election campaigns were marred by violence against opposition candidates, observers say Museveni allowed opposition candidates a freer hand to campaign this year, perhaps thinking that allowing true competition would win him points with voters.