Senegal's President Macky Sall on Monday urged participants in a national dialogue to reach a consensus on a date to hold a delayed presidential election, failing which he will ask the Constitutional Council to find his replacement when his mandate ends on April 2.

The West African nation, set to become an oil and gas producer by the end of the year, has been thrown into an unprecedented political crisis after Sall postponed the election initially scheduled for February 25.

Senegal's Constitutional Council, the highest election authority, later ruled that Sall's decision to postpone the election, and a subsequent 10-month postponement voted by parliament, were unconstitutional.

The electoral crisis has led to violent protests and warnings of authoritarian overreach in one of coup-hit West Africa's more stable democracies.

Sall has declared that his mandate will end on April 2 as stipulated by the constitution so as to assuage fears he wanted to extend his rule in the country. However, the process to elect a new president was unlikely to be concluded by that date.

"If we reach a consensus, I will set the date for the election," Sall said late on Monday while concluding the first of two days of the national dialogue. Participants included some candidates, political parties, civil society and traditional and religious organisations.

"Otherwise, I will ask the Constitutional Council to find my a replacement on April 2," Sall warned.

The talks were boycotted by 15 of the 19 approved candidates who want him to hold the election as soon as possible and leave office when his mandate ends on April 2.

Sall told the national dialogue that the government will propose a general amnesty for those detained between 2021 and 2024 due to the political crisis.

The amnesty could see the release of firebrand opposition leader Ousmane Sonko who was excluded from the race, and his handpicked successor Bassirou Diomaye Faye, who are both detained.