Mikhail Khodorkovsky, a Russian former oil tycoon, has ended a two-day hunger strike after learning that Dmitry Medvedev, the Russian president, was made aware of his complaints about his detention.
Khodorkovsky said on Wednesday a decision last week to extend his detention in Moscow in advance of a new trial violated a law signed by Medvedev earlier this year, and demanded that he be informed.
In a statement, Khodorkovsky said the order to extend his detention by three months violated legal amendments that had been approved by Medvedev.
Khodorkovsky's complaint was submitted to the head of Russia's supreme court. It was also written on behalf of Platon Lebedev, his former business partner, whose detention was also extended.
"Now that it has been officially announced that Medvedev has been informed about the crux of the problem, I don't consider it necessary to insist on the form of discussion" within the government, Khodorkovsky said.
"The aim of my appeal has been achieved. I have ended my hunger strike," he said on his legal team's website.
Natalya Timakova, spokeswoman for Medvedev, said he was "familiar" with Khodorkovsky's May 17 open letter to the head of the supreme court.
Khodorkovsky, 46, is already serving an eight-year sentence for tax evasion and fraud in a case that he claimed was politically motivated by his opposition to then-president Vladimir Putin.
Once Russia's richest man, Khodorkovsky could get 22 more years if convicted for oil theft.
He is due for release next year.
The May 14 decision by Moscow's Khamovniki district court to extend Khodorkovsky’s detention prompted his hunger strike, according to the letter.
The court ruling ignored recent changes in Russia's criminal procedural code, he said.
His aim was to "reduce opportunities for arbitrariness and corruption", the statement said.
Khodorkovsky has said he hopes Medvedev will follow through on promises to tackle corruption in the legal system and ease restrictions on the opposition.
However, critics say little has changed since he replaced Putin in 2008.
Death in prison
Medvedev signed a law banning the pre-trial detention of suspects accused of economic crimes after the death in prison of a tax lawyer awaiting trial drew international condemnation.
Khodorkovsky, the former head of Yukos, the Russian energy company, has been in prison since 2003 and has previously staged several brief hunger strikes.
His supporters have repeatedly staged protests outside the court hearings.
They have said that the case is politically motivated - part of a state crackdown on opponents of Putin, now Russia's prime minister.
The Russian government insists Khodorkovsky committed massive financial crimes to acquire his fortune.