Allegations of human rights abuses have been made by the legal team representing the executives of the Yukos oil giant imprisoned in Russia.
Defence lawyers say Alexei Pichugin, the former head of security at Yukos, has been injected with mind-altering drugs to force him to testify against Mikhail Khodorkovsky, the former chief executive of Yukos, arrested last month on charges of fraud and tax evasion.
The charge is in a dossier prepared by the international defence team working for Mr Khodorkovsky, Mr Pichugin and Platon Lebedev, the former president of Yukos. The document, compiled by Amsterdam and Peroff, a Toronto-based law firm, called the case "a watershed event that has taken on universal significance".
The document included an appeal to the international community to support Mr Khodorkovsky, and claimed that the case is part of an attack on civil liberties in Russia which could affect other businessmen and foreign investors. It also accused the prosecution of violating human rights guaranteed by the Russian constitution "in its rush to prepare a series of political show trials" ahead of parliamentary and presidential elections.
The defence lawyers say that the courts that have been hearing the cases against the men are in the grip of the Kremlin, which is rumoured to be behind the campaign against Mr Khodorkovsky. The dossier states: "[The defendants'] ability to receive an impartial judgment from Russia's government-controlled court system is virtually non-existent."
The oil tycoon is thought to have antagonised the Russian government by funding parties opposed to the administration of President Vladimir Putin, which he accuses of authoritarianism. European Union officials were expected to broach the issue at a meeting with Mr Putin yesterday.
The defence document said that the pre-trial hearings had taken place in secrecy, with even the lawyers of the three men sometimes excluded, which has given rise to fears that their trials will also be held behind closed doors.
The lawyers alleged that they had not been given proper access to their clients. In addition, they claim that hundreds of files and documents relating to the case were confiscated when the Moscow office of Anton Drel, Mr Khodorkovsky's most prominent local lawyer, was raided last month by the security services.
According to the lawyers, both Mr Lebedev and Mr Pichugin have been treated "inhumanely", and Mr Lebedev, who has a heart condition, has been refused access to proper medical attention. The document continues: "The FSB has tortured Mr Pichugin and injected him with psychotropic drugs. The FSB is brutalising Mr Pichugin with a view to turning him into a witness who will testify against the principals."
The Russian embassy in London said the case was a "purely judicial matter" and consequently it could not comment on the allegations.Reuse content