Mikhail Khodorkovsky, the jailed Russian oil tycoon, has derided efforts by the president, Dmitry Medvedev, to improve the rule of law in the country, saying reform is futile as long as his controversial guilty verdict remains in force.

“In which dusty cellar did they dig up the poisonous Stalinist spider who wrote this drivel?” Mr Khodorkovsky asked just hours before a Russian court rejected his appeal against a politically charged theft and money laundering conviction in December, while reducing his sentence from 14 years to 13. “What long-term investments can be spoken of with such a justice system? There can be no modernisation at all without a clean-up of these cellars.”

Critics said the ruling highlighted the limits of Mr Medvedev’s drive to strengthen the independence of Russia’s courts.

“We are witnesses to yet another act of shameless, selective and illegal political reprisal that has been continuing for eight years,” said Yury Schmidt, a lawyer for Mr Khodorkovsky.

Read the full version of the article on the Financial Times.