The authorities in Congo-Brazzaville have submitted the names of eight presidential aspirants to the constitutional court for validation ahead of the 21 March election.

President Denis Sassou Nguesso will face seven challengers including former Finance Minister Mathias Dzon and Guy-Brice Parfait Kolelas, the son of a former prime minister.

Mr Sassou Nguesso, 77, is seeking a fourth term. He has been in power since 1979, except for a five-year period after losing elections in 1992.

Others in the presidential race are Albert Oniangue, a former aide-de-camp of Mr Sassou Nguesso, former MP Joseph Kignoumbi Kia Mbougou, customs official Anguios Nganguia Engambe, MP Michel Mboussi Ngouari and Deve Mafoula, a 38-year-old aspirant.

The largest opposition group, the Pan-African Union for Social Democracy (UPADS), has said it will boycott the polls.

The constitution was changed in a referendum in 2015 to remove term and age limits.

Mr Sassou Nguesso's victory in 2016 was marred by violence and allegations of fraud.