A French investigation has found that a missile attack which brought down the Rwandan president's aircraft in 1994 and prompted the country's genocide, was not carried out by close aides of Paul Kagame, the current Rwandan president.

The findings essentially clear several people close to Kagame, who was the leader of the Tutsi fighters at the time of the assassination of then-president Juvenal Habyarimana, a Hutu.

French judges had filed preliminary charges against Kagame's allies and were investigating the incident because a French air crew were killed in the air crash.

The Rwandan government praised Tuesday's conclusion, which is in line with its own investigation that pointed the finger at Hutu groups.

After the April 1994 crash, fighters from the Hutu ethnic majority quickly set up roadblocks across the capital, Kigali.

More than 500,000 Tutsis and moderate Hutus were massacred in 100 days of frenzied killing that was stopped when Kagame's Tutsi group, the Rwandan Patriotic Front, toppled the Hutu groups.

Bernard Maingain, a lawyer who represented seven Rwandans under investigation, said the findings "put an end to more than 16 years of manipulation and lies".

"Our clients who were unjustly accused and investigated for years have now been proved right," he said.

His comments were echoed by the Rwandan government.

"Today's findings constitute vindication for Rwanda's long-held position on the circumstances surrounding events of April 1994," Louise Mushikiwabo, the Rwandan foreign minister, said in a statement.

"It is now clear to all that the downing of the plane was a coup d'etat carried [out] by extremist Hutu elements and their advisers."

The French investigation has at times created a rift between France and Rwanda.

The delivery in 2006 of arrest warrants for people close to Kagame by a now-retired French anti-terrorism magistrate led to a break in diplomatic ties between France and Rwanda, which were re-established only in 2009.