An opposition group in Niger has called for the ouster of President Mamadou Tandja, following a referendum designed to keep him in power.
The United Front for the Safeguard of Democratic Assets, known by its French acronym FUSAD, says last week's vote to change Niger's constitution was illegal.
In an interview with VOA English to Africa service, a leading member of FUSAD, Maru Amadou, accused Mr. Tandja of corruption and said the people of Niger should "fight against his presidency until he falls."
Supporters of Mr. Tandja have dismissed FUSAD's pronouncement, calling it baseless and unpatriotic.
Electoral officials in Niger said 92 percent of voters approved the constitutional changes that will allow Mr. Tandja to seek a third term in office.
Opposition parties that boycotted the vote say they will challenge the results.
Mr. Tandja pushed ahead with the referendum over the objections of parliament and Niger's constitutional court, which ruled the vote illegal. The president has dissolved both bodies and currently is ruling by decree.
Mr. Tandja says Niger's people want him to finish several foreign-backed projects to develop the impoverished nation's economy.
The government is working with foreign investors on 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.