Chadians voted Monday in an election aimed at ending three years of military rule but dismissed by opponents of junta leader Mahamat Idriss Deby Itno as a fix following violent repression.

They will choose whether to extend three decades of Deby family rule, in a country crucial in the fight against jihadism across the Sahel desert region.

Deby's main rival for president is Prime Minister Succes Masra, denounced as a stooge by critics in the absence of any other serious challengers.

Both men have vowed a first-round win in the polls, which international rights groups warn will not be free or fair.

"All those who have shown they want massive change must go and vote in massive numbers, peacefully," Masra, dressed in a blue boubou, said after voting.

Shortly after polls opened, turnout appeared relatively slow at five voting stations where AFP was present.

"I'm proud of myself, I'm free and very happy to have voted for change," Yolane Madjilar, 58, enthused at a centre set up along a roadside in Ardep Djoumal district.

"I don't like fraud, if someone comes with me this evening, I'll go and observe the counting," she said.

Early in the campaign, observers predicted a massive win for Deby, 40, whose main rival has been killed and others banned from standing.

However, economist Masra, also aged 40, has ramped up considerable support on the stump in recent weeks and could force a second round.

- Proclaimed by generals -

Surrounded by armed presidential guards, Deby was inaccessible to reporters but after voting declared his "commitment" to a "return to the constitutional order", his Facebook page said.

He was proclaimed transitional president by 15 generals in 2021 after his father, longtime leader Idriss Deby Itno, was killed in a gun battle with rebels after 30 years in power.

Known as MIDI for his initials and as "the Man in Dark Glasses", Mahamat promised an 18-month transition to democracy but later extended it by two years.

Opposition figures have since fled, been silenced or joined forces with Deby, while the junta has eliminated any attempts by civil society to campaign against it.

On October 20, 2022, the army and police opened fire on demonstrators protesting the transition extension, including members of Masra's party, The Transformers.

At least 300 young people died according to international NGOs, or about 50 according to the regime.

Deby's cousin and chief election rival Yaya Dillo Djerou was shot point-blank in the head in an army assault on February 28, according to his party.

Masra was among the opponents driven out of the country but later returned and was named prime minister in January.

The eight other candidates, either little known or considered not hostile to the regime, are not expected to win many votes.

- Not 'free or democratic' -

The International Federation for Human Rights (FIDH) has warned that the election appears "neither credible, free nor democratic".

It noted "increasing human rights violations", including Dillo's killing.

The International Crisis Group (ICG) also warned that "a number of problems in the run-up to the balloting cast doubt on its credibility".

These include measures that allow officials to publish only regional tallies of votes rather than posting the results at individual polling stations -- making it impossible for observers to verify the vote count.

ICG also cited Chad's Constitutional Council excluding 10 rival candidates from the vote in Deby strongholds.

As for Masra, it said: "A significant proportion of his constituency now considers him to have become a stooge of those in power".

Some analysts say however that Masra may be genuinely aiming to become president.

- Poverty drives votes -

More than 8.2 million people are registered to vote in the largely desert central African country, ranked by the United Nations as the fourth least-developed country in the world.

With a third of inhabitants aged between 10 and 24, many are voting for the first time.

For 26-year-old literature student Idriss Amidou in N'Djamena, Deby "is the only candidate who offers any hope" and the ruling family "knows how to run the country".

But Eric Bendiguim, 25, a law student at N'Djamena University, said his first-ever vote would go to Masra.

"MIDI has already failed," he said.

"We don't have roads. We don't have electricity. We don't have good schools. We don't have enough to eat."Voting is due to end at 5:00 pm (1600 GMT), with results expected on May 21 and a possible second round on June 22.