Officials are counting votes in Mali, after Sunday's runoff vote to choose the troubled country's next president.
Mali's Ministry of Territorial Administration says it will announce full provisional results on Wednesday.
The election put former prime minister Ibrahim Boubacar Keita against former finance minister Soumalia Cisse, after neither candidate won a majority in the first round of voting last month.
Election observer missions from the European Union and the Economic Community of West African States said Monday the runoff vote went well.
But Cisse's campaign director issued a statement Monday alleging vote rigging, ballot stuffing and intimidation of Cisse supporters. He said the campaign found ballot boxes in mosques and a box stuffed with ballots in a voting office at the start of polling Sunday.
There was no immediate reaction from Keita's campaign.
EU chief observer Louis Michel called for candidates to respect results and use legal means, if necessary, to contest them.
"We make this call to the two candidates," he said. "We hope that the loser will respect the winner and vice versa, and I think we can be reassured to a certain degree on that front. This election, with regard to international democratic standards, is a success. It's an election that will allow Mali to take the final steps to returning to democratic rule and begin to deal with its economic and internal political problems."
The Cisse campaign made similar accusations after the first round but Mali's Constitutional Court dismissed them when it confirmed the first round results last Wednesday.
Keita won almost 40 percent of the July 28 vote, while Cisse earned about 20 percent.
The two men ended up in opposing camps following the 2002 presidential win by Amadou Toumani Toure, who was overthrown in a March 2012 military coup.
The election - the country's first since 2007 - is seen as crucial to unlocking nearly $4 billion in promised international aid that was suspended after the coup last year plunged the country into chaos.
In the chaos that followed, ethnic Tuareg separatists seized towns and cities in Mali's northern desert with the help of several Islamist groups.
Those seizures and Islamist threats to Bamako prompted former colonial power France to deploy troops earlier this year to push the Islamists back into desert areas.
A U.N. peacekeeping force of 12,000 troops began providing security to Mali in July, as the last of the French forces continued preparations to leave the country by the end of the year.