France has started a judicial investigation of six close allies of Rwanda's President Paul Kagame, legal sources say.
The six, who include the defence minister and army chief, are accused of carrying out the attack which sparked the 1994 genocide.
Rwanda previously broke diplomatic ties with France over similar accusations.
Relations improved when President Nicolas Sarkozy visited Kigali in February.
Correspondents say the investigation is part of the continued improvement in ties, as it would allow outstanding arrest warrants to be dropped.
Officials say the six were questioned by a French judge last week in Burundi.
They have denied all wrongdoing.
The shooting down of a plane carrying Rwandan President Juvenal Habyarimana is seen as the trigger for the slaughter of some 800,000 ethnic Tutsis and moderate Hutus by Hutu extremists.
France accuses troops loyal to President Kagame of carrying out the attack.
Correspondents say this is an extremely sensitive matter for Mr Kagame, a Tutsi, as he bases his legitimacy on coming to power to end the genocide.