Rwandan President Paul Kagame has once again accused France of "participating" in the 1994 genocide in an interview to mark the 20th anniversary of the mass killings.

Kagame gave an interview - to be published on Sunday - to the weekly Jeune Afrique, in which he denounced the "direct role of Belgium and France in the political preparation for the genocide".

"Twenty years later, the only thing you can say against them (the French) in their eyes is they didn't do enough to save lives during the genocide," Kagame told Jeune Afrique.

"That's a fact, but it hides the main point: the direct role of Belgium and France in the political preparation of the genocide and the participation of the latter in its very execution," Kagame said.

He also accused French soldiers who took part in a military humanitarian mission in the south of the former Belgian colony of being both accomplices and "actors" in the bloodbath.

Rwanda is marking the 20th anniversary of the atrocities that claimed at least 800,000 lives, mainly of minority Tutsis.

Paris has repeatedly denied the accusations and insisted that French forces had striven to protect civilians.

Kagame's FPR rebels overthrew the Hutu-led government, and his party still controls the government, but many of those accused of the worst crimes of the war escaped, allegedly under the cover of a French military mission.

In 2008, a report by Rwanda's MUCYO commission of inquiry concluded that France had trained the armed groups that carried out killings and French troops had taken part in massacres. It accused 13 politicians and 20 officers by name.

Kagame's assertions came as relations between Kigali and Paris - which were completely frozen from 2006 to 2009 - have improved, notably since France last month, in a landmark ruling, sentenced former Rwandan army captain Pascal Simbikangwa to 25 years in prison for his role in the massacres.

It was the first trial in France to punish those responsible for the three-month wave of violence.

French Justice Minister Christiane Taubira will be on hand in Kigali on Monday at events marking the sombre anniversary.