Congolese opposition leader Moise Katumbi has filed his candidacy to run for president in December polls during which President Felix Tshisekedi will seek re-election for a second term in office, his party said on Wednesday.

Katumbi, a millionaire businessman and former governor of the copper-rich Katanga region, will also be competing against Martin Fayulu - who came second in the last election - and Nobel Prize-winning gynaecologist Denis Mukwege among others.

Tshisekedi, the son of Congo's long-term opposition leader Etienne Tshisekedi, had a turbulent first term embroiled in economic hardship, disease outbreaks and a surge in militia attacks in the east.

"Our country is condemned neither to war, nor to insecurity, nor to bad governance, nor to repeated violations of the rule of law and freedoms," Katumbi said in the statement.

His Ensemble pour la Republique party will reveal a programme in coming weeks that it says will aim to restore security, create jobs and improve social services.

While Tshisekedi came to power promising to end decades of political repression and corruption, rights groups, international allies and rivals accuse him of being just as repressive as his predecessors.

His government denies accusations that rights and liberties are being curbed in Congo.

The months leading up to the Dec. 20 vote have been tense, with complaints about delays and alleged irregularities in voter registration that have sparked protests.

The spokesman for Katumbi's party, Cherubin Okende, was killed in July.

Ensemble pour la Republique denounced a "dramatic context of repression", citing Okende's assassination and a crackdown on opposition protests last month.

Katumbi, 58, left the Democratic Republic of Congo in 2016 after he was accused by the government of hiring mercenaries as part of a plot against Tshisekedi's predecessor Joseph Kabila.

He was also sentenced to three years in prison in absentia that year for real estate fraud - charges he said were politically motivated.

Katumbi was barred from returning to the country to take part in the last election in 2018, the results of which were widely contested.

He returned home in 2019 after his fraud conviction was overturned and prosecutors dropped their investigations into the mercenary accusations.

Katumbi's pardoning was part of move by Tshisekedi to signal a new era of political openness. Other indicted politicians and hundreds of prisoners were also cleared.