Andrei Nekrasov said "Rebellion: The Litvinenko Case," would screen at the prestigious festival on Saturday.
Trade magazine Variety said the festival would announce the addition to its schedule later Wednesday. Nekrasov, co-director Olga Konskaya and Litvinenko's widow, Marina, are expected in Cannes for the screening, Variety said.
Litvinenko, a former KGB agent turned Kremlin critic, died in London in Nov. 23, several weeks after being poisoned with the radioactive element polonium-210. On his deathbed, the 43-year-old Litvinenko accused President Vladimir Putin of being behind his killing.
British prosecutors announced Tuesday that they were charging Andrei Lugovoi, a former KGB bodyguard, with the murder and would seek his extradition from Russia.
Lugovoi strongly denied involvement and said the charge was politically motivated. Russia said it would refuse an extradition request.
Nekrasov, a friend of Litvinenko, had been making a film about the ex-spy before he was poisoned.