The Democratic Republic of Congo and Rwanda clashed on Saturday over the next leader of the Organisation Internationale de la Francophonie, as the long-running tensions between the two neighbouring countries spilled into the contest to head the 53-member body.

The race for secretary-general of the OIF, whose summit opens in Cambodia on Sunday, has emerged as a significant point of friction between Kinshasa and Kigali, which are already locked in a cross-border conflict.

French President Emmanuel Macron, who arrived in Phnom Penh on Saturday, has asked Rwanda to pull its candidate, incumbent secretary-general Louise Mushikiwabo, from the race in favour of a compromise choice ahead of the vote scheduled for Monday.

Mushikiwabo is seeking another term and faces three other contenders, among them Juliana Lumumba of the DR Congo, the daughter of the country's national hero Patrice Lumumba.

After Jeune Afrique magazine reported Macron's intervention, Rwandan Foreign Minister Olivier Nduhungirehe said his country had "rejected" the French request.

The DR Congo, the world's second-largest French-speaking country, has threatened to leave the organisation altogether if Mushikiwabo is re-elected on Monday, according to several sources.

Kinshasa accuses Rwanda of backing the activities of the M23 armed group operating inside Congolese territory, an allegation that Kigali denies.

On Saturday, the DR Congo signalled it was willing to withdraw Lumumba's candidacy if Rwanda reciprocated, clearing the way for a third candidate capable of building consensus and unity within the organisation.

"We have called on all member states to work towards a consensus and, in that spirit, we would be prepared to withdraw our candidate's nomination in order to facilitate the emergence of a consensus," DR Congo's Foreign Minister Therese Kayikwamba Wagner said in Phnom Penh.