Voters in Senegal went to the polls on Sunday to elect mayors and local representatives in a vote seen as a key test of support for President Macky Sall.

The election is the first in the West African country since deadly riots erupted last year following the arrest of opposition leader Ousmane Sonko.

The poll, which comes five months ahead of an eagerly awaited general election, is also the first since Sall won a second term in 2019.

The president has come under increasing criticism since then, facing accusations of arranging court cases against his rivals and of planning a bid for a third presidential term in 2024.

Long lines had formed outside polling stations before they opened at 8 am.

Over six million Senegalese, around a third of the population, are eligible to cast votes for the mayors of more than 500 townhalls as well as the heads of 40 administrative areas known as "departments."

Ibrahima Dieng, a 28-year-old mechanic, was among the first to cast his ballot at a primary school in the capital Dakar's Yoff district.

"Voting is our only way of having a say in the running of the country," he said.

Senegal was rocked by several days of clashes and looting in March 2021 after opposition leader Sonko was summoned to court to answer charges of rape in a case that he said was politically motivated.

At least 12 people were killed nationwide, a toll that shocked a country considered a beacon of stability in a volatile region.

Sall, 60, was first elected in 2012 on promises to help the poor in the nation of 17 million people.

He is well respected on the international scene, but his critics view him as serving the business interests of Senegal's former colonial power France.

The political opposition also fears that Sall will seek to exploit constitutional changes approved in 2016 to argue that a two-term limit for presidents does not apply, and run again.

Several of his ministers are standing in Sunday's vote, including Health Minister Abdoulaye Diouf Sarr, who is running for mayor of Dakar.

Sonko, a failed 2019 presidential candidate, is running for mayor in the southern city of Ziguinchor.