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There has been heavy gunfire in the capital of Niger, in an area where several government ministries - including the president's office - are located.
The Reuters news agency has quoted what it describes as an intelligence official saying it was a coup attempt.
A government source has told the BBC that President Mamadou Tandja and his cabinet ministers are being held by the military at the presidential palace where they were holding the weekly cabinet meeting.
Political tension has been high in Niger in recent months, over President Tandja's extension of his stay in office.
The BBC's Idy Baraou reports
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