France's Supreme Court has overruled a decision to hand over a Rwandan genocide suspect to an international tribunal in Tanzania, his lawyers say.
Mr Ntawukuriryayo was in hiding in France for years
Dominique Ntawukuriryayo is accused by the International Criminal Tribunal for Rwanda of co-ordinating the killing of up to 25,000 Tutsis in April 1994.
His lawyer, Thierry Mausis, told the BBC an earlier ruling was overturned because of procedural violations.
Two other Rwandan suspects held last year in France were subsequently freed.
Mr Ntawukuriryayo, born in 1942, was a sub-prefect in the area of Gisagara at the time of the five-day killings at Kabuye Hill.
Thousands of Tutsis had gathered there and were told they would be safe.
He was arrested the southern French town of Carcassonne last October.
One of his lawyers, Philippe Greciano, told French media that the lower court had failed to examine a "report outlining the various procedural steps allowing the indictee to defend himself".
The case will now return to a lower court, which will be asked to review it.
In September, a Paris appeals court ordered the release of Wenceslas Munyeshyaka, a Catholic priest, and Laurent Bucyibaruta, a former government official.
The court said the warrants issued by the ICTR, based in Tanzania, were "invalid".
The ICTR later withdrew the warrants and asked the French authorities to prosecute them - to the anger of the Rwandan government.
Some 800,000 Tutsis and moderate Hutus were killed during the 100-day massacre in 1994.
Since 1997, the ICTR has convicted 29 ringleaders of the genocide and acquitted five people.
It is due to finish its work by the end of the year.