A documentary about the murder of Alexander Litvinenko is to receive its world premiere at the Cannes Film Festival in France.

The Litvinenko Case will be screened on the weekend.

Mr Litvinenko, a strong critic of the Russian president, died in a London hospital from radiation poisoning.

The film, directed by his friend Andrei Nekrasov, follows the 43-year-old up to his last days in hospital.

On his death-bed, Mr Litvinenko accused President Putin of being involved in his death.

The documentary contains interviews with former KGB agents and is highly critical of the Russian authorities.

In the film, Mr Litvinenko's supporters, including London-based tycoon Boris Berezovsky, accuse the Kremlin of ordering his assassination.