"He has announced his intention to formally challenge the extradition request and to demand his immediate release," one of Mbarushimana’s lawyers, Nick Kaufman, said in a statement to AFP.
"He strongly denies any involvement in the crimes he is accused of," added Kaufman, a former prosecutor at the International Criminal Court.
Mbarushimana, the exiled leader of the Rwandan Hutu rebel group the Democratic Forces for the Liberation of Rwanda (FDLR), was given refugee status in France in 2003.
French authorities arrested Mbarushimana, 47, on a warrant issued in September by the ICC in The Hague.
Mbarushimana faces five charges of crimes against humanity and six war crimes charges for murders, rapes, torture and destruction of property in the eastern DRC in 2009.
The crimes were allegedly committed during a series of "widespread and systematic attacks" by FDLR fighters against civilians in the North Kivu and South Kivu provinces.
Prosecutors say there are grounds to believe Mbarushimana "personally and intentionally contributed" to plotting "widespread and systematic attacks against the civilian population in order to create a humanitarian catastrophe" which could be exploited for political gain.
Mbarushimana will on 20 October appear before the appeals court in Paris, which will review the application of his delivery to the ICC.
Mbarushimana’s lawyer argues that the defendant has lived in France since 2003, well before the date of the crimes alleged against him.