(Corrects Dec. 28 story to clarify in paragraph 5 that official police estimate was 5,000 protesters)
NIAMEY, Dec 28 (Reuters) - Thousands of opposition supporters staged a protest rally on Saturday against what they said was the failure of President Mahamadou Issoufou to improve living standards in Niger, one of the world's poorest countries.
The rally, in the capital Niamey, was the largest in Niger since pro-democracy protests against then-President Mamadou Tandja that helped to block his bid to serve a third term and ushered in a military coup that toppled him in February 2010.
It was the first public show of strength by the Alliance for the Republic, Democracy and Reconciliation in Niger (ARDR), a coalition of 15 opposition parties formed in October. Last month, a court lifted a government ban on opposition marches.
Police sources, who asked not to identified, said some 20,000 people attended Saturday's rally, while organisers put the figure at 30,000. The National Police said in an official statement around 5,000 demonstrators took part.
"Mahamadou Issoufou promised an end to food insecurity but the population continues to be decimated by hunger and thirst," said Amadou Hama, president of the National Assembly whose Nigerien Democratic Movement (MODEN) broke away from the ruling coalition this year.
The ARDR was formed in response to the creation of a national unity government by Issoufou, including breakaway members of MODEN and former president Tandja's National Movement for the Development of Society (MNSD).
Hama and MNSD leader Oumarou Seyni are regarded as the main challengers to Issoufou for the 2016 presidential election.
Niger, with a fast-growing population of 17 million people, has some of the lowest government revenues per capita in Africa despite the start of oil production in 2011. Output is running at around 16,500 barrels a day, the IMF said in September.
Niger, the world's fourth largest uranium producer, is also seeking to renegotiate long-term mining contracts with French nuclear power firm Areva to increase tax revenues. (Reporting by Abdoulaye Massalatchi; Writing by Daniel Flynn; Editing by Jon Boyle)