The ruling party of Senegalese President Macky Sall has conceded defeat in the capital Dakar and the southern city of Ziguinchor in local elections widely seen as a test of Sall's popularity.

The West African country voted in municipal and regional elections on Sunday amid growing tensions over whether Sall will seek to extend his rule beyond the two-term limit in a nation long considered one of Africa's most stable democracies.

The elections were seen as a bellwether for a legislative election in June and the battle for the presidency in 2024.

"Our will to capture Dakar and Ziguinchor, in particular, was not conclusive," said the ruling party coalition, Benno Bokk Yaakaar, in a statement late on Sunday. It congratulated the other candidates and called the vote a triumph of democracy.

According to preliminary results, the leading candidate for mayor of Dakar was Barthelemy Dias, who posted videos on social media of large crowds in the streets celebrating his victory.

Dias is an ally of former Dakar mayor Khalifa Sall, no relation to the president, who was jailed in 2018 on corruption charges in what many saw as a move by Macky Sall to silence a political rival.

Sall, 60, came to power in 2012 and won re-election in 2019.

He has not ruled out seeking a third term following a constitutional referendum in 2016 that could be used to reset the clock on his term of office. Similar constitutional devices were used by Guinea's ousted President Alpha Conde and Alassane Ouattara of Ivory Coast to run again despite violent protests in both countries.

Another rival of Sall's, Ousmane Sonko, was the preliminary winner in Ziguinchor, capital of Senegal's Casamance region.

Sonko was arrested last year following a rape accusation, which he denied. His arrest sparked days of violent protests and accusations again that President Sall was interfering with the judiciary to target potential challengers.