20091231

NIAMEY (Reuters) - Niger's President Mamadou Tandja tightened his grip on power in the Saharan uranium-producer on Wednesday as his ruling party won a municipal vote denounced by rivals as illegal.

Tandja faces growing international isolation after amending the constitution in August to extend a five-year rule in office that was originally due to have ended last week.

His National Movement for a Society of Development (MNSD) party won 1,939 of a total 3,600 seats in 264 local authorities in Sunday's poll, which opponents urged voters to boycott. The MNSD already won a national parliament majority in October and Tandja has seen his own powers boosted by the new constitution.

The United States last week terminated trade benefits for Niger, the latest in a line of measures taken by African neighbours, the European Union and others to punish Tandja.

However analysts question the impact of such measures while Niger continues to see revenues from exports of uranium, used notably by France as a part of its reliance on nuclear power.