Former Russian oil tycoon Mikhail Khodorkovsky has been found guilty of embezzlement at his politically charged second trial in Moscow.
The judge said Khodorkovsky and his business partner Platon Lebedev were guilty of stealing from their firm Yukos and laundering the proceeds.
Khodorkovsky is already serving an eight-year sentence for fraud and tax evasion from his 2005 trial.
The US and Germany were highly critical of the verdict.
US Secretary of State Hillary Clinton said the trial raised "serious questions" about the rule of law in Russia and the verdict would have a "negative impact on Russia's reputation".
German Foreign Minister Guido Westerwelle said he was "very worried" by the conviction.
"The way the trial has been conducted is extremely dubious and a step backward on the road toward a modernisation of the country," he said in a statement.
"It is in the interest of our Russian partners to take these concerns seriously and to stand up for the rule of law, democracy and human rights."
Richard Ottaway, chairman of the UK parliament's Foreign Affairs Committee, said the "due process of law that we in the UK would recognise" had not been followed.
Khodorkovsky's lawyers say the verdict was the result of official pressure.
Khodorkovsky, 47, was due to be released next year, but the new convictions could see him jailed for much longer.
The two defendants were led into court in handcuffs by armed guards.
In the sealed glass dock Khodorkovsky - once Russia's richest man - waved at his parents, the small courtroom packed with journalists and cameras.
Several hundred demonstrators could be heard outside the courtroom, chanting "Freedom!" and "Put Putin [the Russian prime minister] in jail!"
Police made a number of arrests.
Judge Viktor Danilkin read out the first few pages of the verdict before asking camera crews to leave the courtroom.
"The court has established that Mikhail Khodorkovsky and Platon Lebedev committed embezzlement acting in collusion with a group of people and using their professional positions," Judge Danilkin said.
Delivering the full verdict and sentence is expected to take several days.
Khodorkovsky's lawyers have already said they will appeal.
In the latest trial, Khodorkovsky and Lebedev are accused of stealing hundreds of millions of tonnes of oil from the now defunct Yukos oil company and laundering the proceeds, in the years 1998-2003.
He has denounced the charges as rubbish.
Khodorkovsky has said that a state that destroys its best companies and trusts only the bureaucracy and the special services is a sick state.
Many critics believe the government wants the former tycoon kept behind bars for as long as possible because he financed the opposition when Vladimir Putin was president.
Mr Putin - now Russia's prime minister - referred to Khodorkovsky in a televised question-and-answer session last week, when he said he believed "a thief belongs in prison".
One of Khodorkovsky's lawyers, Vadim Klyuvgant, has criticised what he described as "an unjust verdict by a court that is not free", describing it as "shameful for the country".
"If the court were free and independent in issuing its verdict, it would have issued an acquittal. What we heard here confirms that the court has faced pressure," he told reporters.