The president says he needs more time to complete development projects
Niger's president has overwhelmingly won a referendum that will allow him to stay in power beyond the end of his second term in office, results show.
Mamadou Tandja, 71, had already claimed victory before the official announcement, putting up giant posters in the capital thanking the voters.
The election commission said Mr Tandja won more than 92% of the vote.
Opposition groups had urged a boycott and dispute the 68% turnout figure, saying it was as low as 4%.
The BBC's Idy Baraou in the capital, Niamey, says that although Tuesday's voting was not as busy as in previous elections there was a steady trickle of people turning up at polling stations.
Our reporter says the opposition grouping Co-ordination of Democratic Forces for the Republic (CFDR) had no representatives at the electoral commission and was unable to explain how it came up with its figures.
The result means Mr Tandja will be able to go ahead with plans to change the constitution and run for a third term in office.
The president, whose second term ends in December, dissolved both parliament and the constitutional court to push through the referendum.
His backers say he has boosted living standards during 10 years in power and deserves to remain in office.
The president says he needs more time to complete multi-billion-dollar projects such as a uranium mine, an oil refinery and a dam on the River Niger.
But his critics portray him as a classic strongman determined to hold on to power so he can benefit financially from the projects he has started.
The European Union has already suspended an aid payment and warned of "serious consequences" for its co-operation with Niger if the president carries through his plans.