Rwandan President Paul Kagame took a thinly-veiled swipe at France on Monday, saying it was impossible to "change the facts" about the genocide 20 years ago.
"The passage of time should not obscure the facts, lesson the responsibility, or turn victims into villains," he said in a speech during commemorations marking the 20th anniversary of the genocide.
"People cannot be bribed or forced into changing their history, and no country is powerful enough, even when they think they are, to change the facts... After all, les faits sont tetus (facts are facts)," he said, saying the final phrase in French and drawing loud applause in the national stadium.
Rwandan Foreign Minister Louise Mushikiwabo also said France had to face up to the "difficult truth" over its involvement.
Those words lead to angry responses from top ranking French officials.
Edouard Balladur of the centre-right UMP, prime minister at the time of the killings, said Kagame "is constantly seeking to accuse France when he himself has not, after 20 years, been able to bring together the Rwandan people.
"France is in no way complicit in the genocide. On the contrary, it of all countries in the world was the only one that took the initiative to organise a humanitarian operation to prevent widespread massacres," he told Europe 1 radio.
General Jean-Claude Lafourcade, the former commander of Operation Turquoise, the French military mission in Rwanda, also rejected the accusations.
"I find Mr. Kagame's accusations unfounded and unfair - they completely tarnish this day of commemoration for a global human tragedy," he told RTL radio.
Noting that French forces arrived at the end of June 1994, when "90 percent of the massacres" had already been committed, Lafourcade said: "Not a single French soldier was in Rwanda during the genocide."
Earlier in the day, in a sign of the tensions between the two countries French ambassador to Rwanda had been barred from attending events marking the two-decade anniversary of the killing that claimed 800,000 lives, amid a major diplomatic row surrounding France's controversial role in the events of 1994.
"Yesterday night the Rwandan foreign ministry telephoned to inform me that I was no longer accredited for the ceremonies," the French ambassador, Michel Flesch, told AFP.
French Justice Minister Christiane Taubira pulled out of attending Monday's events after Rwandan President Paul Kagame repeated his accusation of French "participation" in the murder of 800,000 ethnic Tutsis.
France has repeatedly denied any complicity in the genocide. The French helped train the Hutu nationalist-controlled Rwandan army prior to 1994 have also been accused of aiding the killers to escape
Although choosing not to send a minister, France had said its ambassador would attend -- a major diplomatic downgrading of its attendance.
Rwandan Foreign Minister Louise Mushikiwabo on Sunday told France to face up to the "difficult truth" over its actions two decades ago.
"For our two countries to really start getting along, we will have to face the truth, the truth is difficult, the truth of being close to anybody who is associated with genocide understandably is a very difficult truth to accept," Mushikiwabo said.