Uganda's president has started mediating talks between Burundi's government and opposition groups that are opposed to President Pierre Nkurunziza's controversial bid for a third term.

Ugandan President Yoweri Museveni met with representatives of the Burundi government and opposition leaders in the nation's capital, Bujumbura, late Tuesday.

Museveni was chosen by regional leaders earlier this month to mediate Burundi's political crisis ahead of presidential elections scheduled for July 21.

Burundi has been on edge since April when the country's ruling party nominated Nkurunziza to be its presidential candidate, sparking violent street protests. The unrest later sparked a military coup that was quickly put down.

Burundi remains tense, with fears growing of a new rebellion based in the country's northern provinces.