Mauritania's main Islamist party said on Monday the country's parliamentary and local elections had been marred by "ballot stuffing" and other forms of fraud.
Tewassoul president Jemil Ould Mansour told a news conference the party had found "serious irregularities" which could discredit Saturday's polls, including "ballot stuffing in some places and the resumption of the vote after the count in others".
"We cannot accept this fact in any way and we have sent a delegation to the (election commission) to talk about it," he said.
He did not say which parties had benefited from the alleged ballot-stuffing, a form of electoral fraud in which people submit multiple ballots during a vote in which only one ballot per person is allowed.
Following independence from France in 1960 and the ensuing one-party government of Moktar Ould Daddah, deposed in 1978, Mauritania had a series of military rulers until its first multi-party election in 1992.
Around a third of its 3.4 million people were eligible to vote in Saturday's elections, seen as a test of strength for President Mohamed Ould Abdel Aziz five years after he came to power in a coup and four years after he won a widely contested presidential vote.
State television put the turnout at around 60 percent, with the ruling Union for the Republic (UPR) widely expected to retain power but with many analysts expecting Tewassoul, only legalised in 2007, to make significant gains.
Around 1,500 candidates from 74 parties representing the administration and the so-called "moderate" opposition were registered to vie for 147 seats in parliament and the leadership of 218 councils.
But Tewassoul was the only member of the so-called "radical" opposition, the 11-party Coordination of Democratic Opposition (COD), contesting the polls. The other coalition partners boycotted the vote.
The electoral commission, which has been drip-feeding results from individual polling stations since Saturday, issued a statement saying the delay in announcing an overall picture was due to the "complexity" of the process and the need to be thorough.