An aide to the Russian judge who convicted Mikhail Khodorkovsky at his second trial last year has said he did not write his own verdict.
Judge Viktor Danilkin resented having to take orders from above during the trial of the former tycoon, Natalya Vasilyeva told Russian media.
The judge denied her allegations, describing them as slander.
The trial for fraud of Khodorkovsky and his business partner Platon Lebedev was widely condemned abroad as unfair.
Already in detention since 2003, he was sentenced to a further six years in prison and is not now due for release until 2017.
Under Russian law, it is for the judge alone to write his verdict, without any interference by other members of the judiciary.
According to Ms Vasilyeva, Judge Danilkin was indignant at having to take orders and was anxious and irritable because of it.
When asked for confirmation of what she had reportedly told Russian media, Ms Vasilyeva's office said she was on holiday.
Speaking to Russian gazeta.ru, a widely read liberal Russian newspaper, she said that the judge had been under "total control", constantly receiving instructions from the Moscow City Court.
Judge Danilkin began writing the sentence but it did not please his superiors, she said.
"As a result he received a different verdict which he was obliged to read out," she told gazeta.ru.
"I know for a fact that the sentence was brought from Moscow City Court," she said.
"And it is obvious that it was written by criminal case appeal judges, that's to say, by Moscow City Court judges."
Ms Vasilyeva said she knew the judges' names but preferred not to give them.
The part of the verdict dealing with sentencing was delivered to Judge Danilkin while he was still reading out the verdict, she added.
Ms Vasilyeva said her information came from "people close to the judge" but she was unable to say how the alleged additional parts of the sentence were passed to the judge.
She said her duties at Moscow's Khamovnichesky Court, where the trial took place, were assistant to the judge and court press secretary.
She told gazeta.ru she did not expect to continue in her post at the court after the interview.
'Nothing but slander'
Responding to his assistant's allegations, Judge Danilkin told Russia's Itar-Tass news agency: "I am sure that the statement by Natalya Vasilyeva is nothing but slander and can be denied through a legal process."
Moscow City Court spokeswoman Anna Usacheva described Ms Vasilyeva's comments as a "provocation" and a "well-planned PR act" ahead of the court's review of an appeal of the verdict.
"I am sure that Natalya Vasilyeva will yet renounce her comments," Ms Usacheva added.
Khodorkovsky, once seen as a political threat to former President Vladimir Putin, was found guilty along with Lebedev at the end of December of stealing billions of dollars from their own oil firm, Yukos, and laundering the proceeds.
The defence had argued that the charges were absurd since the amount of oil said to have been embezzled would be equivalent to the entire production of Yukos in the period concerned.
The US state department said at the time that Washington was concerned by the apparent "abusive use of the legal system for improper ends, particularly now that Khodorkovsky and Lebedev have been sentenced to the maximum penalty".