BBC Correspondent Claire Doole reports: An important prosecution yields little

The prosecution had said the 40-year-old businessman was a threat to society and the hearings took place amidst unprecedented security.

Mr Mikhailov, who is on a number of international wanted lists, was arrested at Geneva airport two years ago.

The authorities tried to bring a charge of money-laundering against him, but had difficulty when they tried to gather evidence in Russia.

Instead, he was charged with three lesser offences, the most important of which was membership of a secret criminal organisation.

Police and prosecutors had argued that Mr Mikhailov had led an illegal gang known as the Solntsevo group.

He was also charged with unlawful residency in Switzerland and falsifying documents in the purchase of a house.

Witness shot dead

The 15-day trial featured 90 witnesses, with many receiving police protection after one was shot dead in Amsterdam last year.

A former senior Moscow police investigator, said to have fled to Switzerland after his life was threatened, told the court the Solntsevo gang was involved in narcotics and arms trafficking.

There were also letters from Interpol implicating Mr Mikhailov in the Russian mafia, while various passports said to have been used by the defendant were also produced.

'I love you'

But the Russian, who has a wife and two small children, was cleared of all but the last minor charge.

He was allowed to walk free from the court after spending two years in jail waiting for the trial.

He immediately thanked the jury, crying: "My heart is full of gratitude...I love you, I love you, I love you."

Later, in a statement, he added: "You have shown to the whole world that democracy, law and justice exists in this country."

Mr Mikhailov faced a maximum of seven and a half years in jail if found guilty and his acquittal is being viewed as a major blow to the Swiss authorities.