Mahamadou Issoufou is considered the favourite after taking the lead in the first round on January 31 [AFP]

The people of Niger have voted for a new civilian president in landmark polls that the outgoing head of the military government said should serve as an example of democracy to the whole of Africa.

Thirteen months after Mamadou Tandja was jettisoned from office over his attempts to amend the constitution, voters headed to the polls on Saturday to choose between a veteran opposition leader and a former ally of the toppled president in the run-off election.

Mahamadou Issoufou, a long-time opponent of Tandja's 10-year rule, is considered the favourite after taking the lead in the first round vote on January 31.

Issoufou took 36 per cent of the vote in that poll, compared to 23 per cent for Seini Oumarou, the 60-year-old leader of Tandja's party and a former prime minister.

Niger's ruling leaders vowed to usher in a civilian government after they took power last year to end a crisis triggered by Tandja's attempts to extend his rule beyond the constitutional limits.

No member of the ruling government was an election candidate.

'Example to Africa'

General Salou Djibo, installed as leader of the country after the February 2010 coup, was among the first to cast his ballot.

"This is a great day for me and for all the people of Niger," he told journalists at a polling station in Niamey, the capital.

"If we can hold a successful election then together we will have accomplished bringing about a democracy that can serve as an example to Africa." 

Issoufou, the leader of the Social Democratic Party, has strengthened his candidacy by forging alliances, especially with Hama Amadou, another former premier under Tandja who garnered 19 per cent in the first round vote.

"We are going to win this election. I have received significant support, including from Hama Amadou," Issoufou told journalists as he voted.

Oumarou, of the National Movement for the Development of Society, was equally bullish, discounting his rival's lead in the first round.

"I am very confident. Politics is not a game of maths. Everyone goes back to zero after the first round," he said at a Niamey polling station.

'Everything is calm'

During the campaign, both candidates promised to dissolve parliament and organise legislative elections for a more representative assembly in the vast, landlocked country on the edge of the Sahara desert.

They also expressed similar goals for Niger, an impoverished nation that has become a base for al-Qaeda-linked fighters.

Both candidates vowed to tackle the poverty that afflicts about 60 per cent of the population, protect against the cyclical food crises, and assure an equitable distribution of the country's wealth from uranium.

Voting appeared to have passed off peacefully, with the independent electoral commission saying it had received no reports of any incident.

There was no immediate word on turnout although a journalist from the AFP news agency said that it appeared to be relatively light in the capital where there was no sign of long queues.

'Republican pact'

Speaking at the Niamey polling station, acting head of state Djibo urged supporters of the two candidates to respect the rule of law and voters to turn out in force.

"I have come here to perform my civic duty and I call on all the sons and daughters of Niger to do the same," he said.

"I also appeal to the two candidates that they respect the outcome once the  results have been declared by electoral commission, and that the loser accepts  his defeat."

Earlier this week, a "republican pact" was signed by which civilian and military authorities have agreed to respect the country's new constitution, adopted at the end of last year.

Since independence from France in 1960, Niger has been wracked by coups and faced a Tuareg rebellion in the north of the country.

In recent years the Sahel country has become one of the bases for Al-Qaeda in the Islamic Maghreb, which has been responsible for kidnappings and killings of Westerners in the region.