Roman Abramovich, the Russian tycoon who owns Chelsea football club, has been drawn into a French investigation into the purchase, by his former business partner, of a spectacular seafront property on the Cote d'Azur.

French investigators reportedly want to question Abramovich as part of an investigation into the circumstances in which another British-based Russian billionaire, Boris Berezovsky, bought the La Garoupe estate in 1997.

Berezovsky's chateau in the walled estate, on the Cap d'Antibes, was searched last month on the orders of a French magistrate acting at the prompting of the French Finance Ministry's anti-money-laundering unit.

Berezovsky was in London at the time and said his 81-year-old mother, who was alone with an employee, had been indisposed by the arrival of masked and armed men who swooped into the property by helicopter and seized documents.

According to yesterday's Nice-Matin newspaper, documents seized in that raid show the involvement of a company controlled by Abramovich in the purchase of La Garoupe for 22 million ($38.5 million).

The judge leading the investigation, Beatrice Del Volgo, has been looking into whether part of the money used by Berezovsky to buy La Garoupe was guaranteed by Sibneft, the oil company controlled by Abramovich.

The two billionaires joined the club of the Russian oligarchs when they benefited from the selling of state assets after the collapse of the Soviet Union. But they are now estranged.

Berezovsky successfully applied for political asylum in Britain after claiming he was being hounded by President Vladimir Putin for his political activities; Abramovich remains close to the Kremlin and is Governor of the Arctic region of Chukotka.

Another Putin opponent, Mikhail Khodorkovsky, the billionaire Russian oil tycoon, was this week found guilty and sentenced to nine years in jail for an array of fraud and tax evasion offences.

Nice-Matin said Del Volgo wanted to question Abramovich on whether Sibneft did help Berezovsky buy the estate. A spokesman for Abramovich denied Sibneft had provided any financial guarantees for the purchase.

Nice-Matin said Del Volgo also wanted to question Abramovich about his own purchase of the Chateau de la Croe, near Antibes.

Abramovich, Britain's richest man, bought the chateau, where the Duke of Windsor set up home after abdicating, for around 15 million last year. The Abramovich spokesman said "any check into Mr Abramovich's property would only confirm that his assets were purchased legally and above board".

Berezovsky said he knew nothing about any involvement by Abramovich in the property and the investigation was instigated by his arch-enemy, Putin.