“The longer you speak with the gangster head of a country, the more victims there will be in the end, until these cannibals are erased from the story," Berezovsky said in a telephone interview with Miriam Elder, the Guardian’s Moscow correspondent, from London.

Cameron is due to hold talks with Putin on Monday, the first British premier to do so since Tony Blair met the powerful leader in mid-2007.

Four former foreign secretaries have called on David Cameron to challenge the Russian government during his trip to Moscow this week.

In a letter to the Sunday Times, Labour's David Miliband, Jack Straw and Margaret Beckett, and Conservative Sir Malcolm Rifkind have asked the Prime Minister to confront President Dmitry Medvedev and Vladimir Putin over failures to protect businessmen.

They say that this failure is resulting in businessmen and lawyers becoming 'victims of an increasingly potent mix of corruption and lawlessness'.

William Browder, has accused David Cameron of going soft on Russia and of naively treating the Kremlin with kid gloves out of a misplaced fear of Moscow. In an interview with The Sunday Telegraph on the eve of the Prime Minister's historic visit to Russia tomorrow, William Browder, the founder of UK-based Hermitage Capital Management, said the British government had shied away from tackling Russia on human rights issues and claimed that the Kremlin was laughing at Mr Cameron behind his back.

“The government needs to be realistic about dealing with Russia. But it doesn't seem to understand its major strength in dealing with Russian officials,” Mr Browder charged.
"Cameron should be warning British companies not to do business in Russia," he said.

Russia's most famous prisoner of conscience has spoken out from behind bars to urge David Cameron to confront the Kremlin on human rights issues when the Prime Minister visits Russia.

In written comments passed to The Daily Telegraph from his prison in northern Russia, Mikhail Khodorkovsky said Mr Cameron should use the fact that top Russian politicians bank, own property, and educate their children in the UK to pressure the Kremlin into becoming "a modern European state."

"I would hope that the British Prime Minister will directly raise questions of corruption and the judicial system in Russia with President (Dmitry) Medvedev," the 48-year-old oligarch-turned-political prisoner wrote.

British Prime Minister David Cameron AFP