The atmosphere was tense but peaceful in Niger on Sunday as the presidential polls closed in the landlocked African country.

Security was tight at the over 25,000 voting stations scattered across the country of some 7.5 million inhabitants as incumbent President Mahamadou Issoufou, who is seeking a second five-year term, promised to deliver a "knockout" blow to his opponents.

Issoufou's main opponent highlighted the link:19049716:political turmoil# that has plagued the resource-rich but impoverished nation since 2013.

Opposition leader Hama Amadou, a former speaker of parliament, broke with Issoufou in that year and was subsequently accused of trafficking children. He fled to France, only to be arrested upon his return in November 2015 and thus conducted his campaign from prison.

The president's 14 rival candidates have already accused him of a plot to rig the election in his favor.

Defense was one of the major themes of the campaign, with Niger facing spillover from Islamist insurgencies in neighboring Nigheria, Mali, and Libya.

Upbeat incumbent

Issoufou was upbeat on Sunday, however, saying that this was a "great day" for the country.

"This is a great day for Niger and for our institutions," the president said to the French-language news outlet La Voix de l'Amerique.

"There will be only one winner, it will be Niger. Niger needs peace and security to continue on the path of progress, economic and social development," said the former mathematician and mining engineer who now leads the Socialist Party.

Results are set to be announced in five days time.

If no candidate is able to security a majority of the vote, a run-off election of top contenders will be called. President Issoufou, however, was confident that this would not be necessary, saying he was "absolutely" confident of his victory.

es/jm (AFP, dpa)