The Democratic Republic of Congo's Supreme Court has rejected a legal challenge to last month's presidential run-off election.
Mr Bemba (r) said President Kabila (r) won fraudulently
Former rebel leader Jean-Pierre Bemba disputed provisional results that gave victory to his rival, interim President Joseph Kabila, with 58.05% of the vote.
US election observer group the Carter Center says there is evidence of vote tampering on both sides.
But it says neither candidate benefited significantly over the other.
According to the country's electoral commission, Mr Kabila won 58.05% of the vote compared to Mr Bemba's 41.9%.
Correspondents say tension is high in the capital, Kinshasa, which is a Bemba stronghold.
Meanwhile there have been clashes in eastern DR Congo where United Nations forces say they have stopped a dissident rebel general from advancing towards Goma.
Supreme Court judge Kalonda Kele said complaints of fraud filed by Mr Bemba were "unfounded", AFP news agency reports.
Last week a protest by Bemba supporters outside the Supreme Court led to violence and the court was set alight.
Tension is high in Kinshasa after last week's unrest
Forces loyal to Mr Bemba, who is also an interim vice-president, were subsequently ordered out of the capital by Mr Kabila.
Ahead of the Supreme Court's ruling the Carter Center urged both parties to remain calm.
It said that in its evaluation of the results it found evidence of significant electoral abuses including:
- Supplemental voter lists through the excessive and irregular exploitation of voting by exemption
- Faulty implementation of the lists of omitted voters
- Questionably high turnout rates in some areas.
But it said the overall number of votes resulting from these abuses were "not of a decisive scale".
"The manipulation we have found was perpetrated by supporters of both candidates and the geographic distribution of the abuses did not benefit one candidate significantly over the other," the Carter Center statement said.
The results have shown a regional divide, with Mr Bemba gaining most votes in the Lingala-speaking west, including Kinshasa, while Mr Kabila won by a landslide in the Swahili-speaking east.
The elections were supposed to draw a line under a five-year conflict in which some four million people died.
The polls were organised under the terms of a 2002 peace deal that drew in the armies of nine other African countries.
Under the deal, former rebels forced were supposed to be integrated into the army but progress has been slow and the three former rebel leaders who are vice-presidents have retained large personal security forces.
The world's biggest peacekeeping force - some 17,000 men - is in DR Congo to prevent unrest.