Russian oligarch Mikhail Khodorkovsky appeared in court to face new charges of embezzlement and money laundering in a case his lawyers say will test President Dmitry Medvedev's promises to reform Russia.
The fate of Khodorkovsky, an oil tycoon who fell foul of the Kremlin under former president Vladimir Putin and was jailed in Siberia for tax evasion and fraud, is being closely watched for any signs of a milder tone under Mr Medvedev.
Khodorkovsky, who wore jeans and carried a black briefcase, was brought by guards to the Khamovnichesky court in Moscow, the first time he has appeared in public in the capital since late 2005. A supporter threw white roses towards him.
Khodorkovsky, handcuffed to a guard, looked straight ahead and did not speak as he was led into the building.
Prosecutors allege he helped embezzle 900 billion roubles (€19.7 billion) and laundered 500 billion roubles (€11 billion), charges that could keep him in jail for 22 years more if found guilty.
Khodorkovsky (45) was convicted in 2005 and is serving a prison term in Chita, about 7,000 km east of Moscow near the Chinese border. He has denied his guilt and blamed senior officials close to Mr Putin, how is now prime minister, for his fate.
Khodorkovsky says he is the victim of corrupt officials who feared his political ambitions and wanted to carve up his YUKOS business empire, which produced more oil than OPEC member Qatar.
Khodorkovsky's lawyers say their client is a political prisoner and the new charges are absurd. They say he is charged with stealing more oil from the YUKOS oil company that he controlled than it produced during the years in question.
His arrest in 2003 by officers of the FSB security service at a Siberian airport shocked Russia's business community, which feared the Kremlin would try to regain control of raw materials companies sold off in the 1990s.
Mr Medvedev, a former lawyer sworn in as president last May, has demanded a clean-up of the Russian court system since Khodorkovsky's sentence and criticised high-level corruption.
"This case of immense importance because of what it will say to all of us about where Russia is going," Robert Amsterdam, a defence lawyer for Khodorkovsky, said by telephone from London before the hearing.
Russian police detained about 10 Khodorkovsky supporters outside the court.