Khodorkovsky described the Moscow appeals court's verdict as 'gibberish' [AFP]

A Russian appeals court has upheld the second conviction of Mikhail Khodorkovsky, the former oil tycoon, but reduced his 14-year prison sentence to 13 years.

The Moscow City Court ruling means Khodorkovsky, the ex-chief of the Yukos oil company, who has been jailed since 2003, will remain in prison well into 2016.

Khodorkovsky, who fell foul of the Kremlin during Vladimir Putin's presidency, and his business partner Platon Lebedev, were initially convicted of fraud and tax evasion in 2005.

The court "imposes on Khodorkovsky and Lebedev punishment in the form of imprisonment for a term of 13 years," said Olga Arochkina, the judge, after the one-day hearing of their appeals on Tuesday.

During the hearing, Khodorkovsky poured scorn on the judges who had written the verdict, a lengthy summary of the trial that spelled out his guilt.

"From which dusty basement did they dig out the venomous Stalinist spider who wrote that gibberish?" said Khodorkovsky.

Karina Moskalenko, one of Khodorkovsky's lawyers, called the one-year reduction of the sentence "cosmetic".

Supporters outside the courtroom yelled out, calling the decision a "disgrace".

In December, the trial judge who convicted Khodorkovsky sentenced him to serve a total of 14 years in prison, counting from his initial arrest at a Siberian airport in October 2003.

Government critics describe the prosecution as part of a Kremlin campaign to tighten state control over oil revenues and punish Khodorkovsky for perceived challenges to Putin, president from 2000 to 2008 and now prime minister.

Source: Agencies