Niger's government and the opposition are at odds over voter turnout in a constitutional referendum that could extend the rule of President Mamadou Tandja.
Electoral officials say voter turnout in Tuesday's poll was about 45 percent in bigger cities and 75 percent in rural areas.
Opposition leaders dispute the figures, saying huge numbers of people stayed away from the polls.
Opposition supporters blocked some polling stations Tuesday, sparking clashes with police.
Niger's election chief, Moumouni Hamidou, acknowledged Wednesday that protests in the western Tahoua region kept 30 polling stations closed. Hamidou said the results will still represent the will of the people.
If approved, the constitutional changes will allow the 71-year-old president to run for office after his second term ends in December.
Electoral officials expect to release final results in three to five days.
Niger's opposition strongly objected to the referendum, and accuses Mr. Tandja of staging a virtual coup.
Mr. Tandja says the people want him to finish several foreign-backed projects to develop the impoverished nation's economy.
The government is working with foreign investors on several infrastructure projects, including a uranium mine, an oil refinery and a hydroelectric dam.
Niger is rich in uranium but its 15 million people are among the world's poorest.
The European Union has suspended aid to Niger, accusing it of "grave violations" of democratic values and the rule of law.
Some information for this report was provided by AFP.