The demonstration was organised by the Coordination of Democratic Forces for the Republic (CFDR), a coalition of political parties, human rights and labour organisations.

Demonstrators carried different placards with peppery messages. They shouted anti-government slogans such as "Down with the dictator", and waved pictures of leading opposition politicians including former prime minister Hama Amandou.

Tandja, 71, a former colonel, was supposed to step down on December 22 after serving two consecutive five-year terms.

But he says the Nigerien people asked him to remain in power in order to complete the multi-billion dollar projects he initiated, which have brought prosperity to the arid nation.

The opposition says it is unconstitutional and will hamper the country’s nascent democracy.

Tandja also dissolved parliament and the constitutional court which had opposed his move to remain in power.

Controversial parliamentary elections held in October were boycotted by the opposition. The disputed poll led the 15-nation Economic Community of West African States (ECOWAS) to suspend Niger's membership and the European Union to suspend aid.

However, West African big neighbour, Nigeria, is mediating in the Niger’s crisis, and talks have begun between the Niger’s administration and the European Commission.