Mauritanians voted on Saturday in a presidential election that incumbent Mohamed Ould Ghazouani is widely expected to win, aiming to boost investment in the West African country as it prepares to start producing natural gas.

Ghazouani, 67, a former top soldier, has promised investor-friendly policies to spur a commodities boom in the country of 5 million people, many of whom live in poverty despite its fossil fuel and minerals wealth.

Polls opened at 0700 GMT. Voting is expected to end at 1900 GMT, and provisional results are expected from Sunday.

Elected for a first term in 2019, Ghazouani is facing a field of six opponents, among them anti-slavery activist Biram Dah Abeid, who came second in 2019 with over 18% of the vote.

Other challengers include lawyer Id Mohameden M'Bareck, economist Mohamed Lemine El Mourtaji El Wafi, and Hamadi Sidi El Mokhtar of the Islamist Tewassoul party.

Casting his ballot soon after polls opened in the capital Nouakchott, 39-year-old geographer Mohamed Cheikh Hadrami said he had voted for a candidate "who will be able to reconcile Mauritanians". He declined to say who he had voted for.

Some 2 million people were registered to vote, with major election issues including fighting corruption and creating jobs for the young.

If re-elected, Ghazouani has promised a natural gas-fired power plant from the Greater Tortue Ahmeyin (GTA) offshore gas project, which is on track to start production by the end of the year. He also pledged to invest in renewable energy and expand gold, uranium, and iron-ore mining.