By John Revill and Oliver Hirt

ZURICH (Reuters) -A concert cellist linked to Russian President Vladimir Putin moved millions of francs through Swiss bank accounts without any proper checks, Swiss prosecutors will allege on Wednesday at the opening of a trial of four bankers accused of helping him.

Prosecutors say that Sergey Roldugin, a close friend of the Russian president according to the indictment and sanctioned by Switzerland, deposited millions of francs in Swiss bank accounts between 2014 and 2016.

The four bankers appeared at Zurich District Court at the start of their trial on Wednesday, accused of lacking diligence in financial transactions.

Prosecutors allege they failed to do enough to determine the identity of the beneficial owner of the funds, according to the indictment seen by Reuters.

The bankers - three Russians who worked in Zurich and one Swiss - all denied the allegations against them at the hearing. They cannot be named under Swiss reporting restrictions.

Roldugin was named the owner of two accounts opened at Gazprombank Switzerland in 2014, into which flowed millions of francs from Russia.

This was despite Roldugin - who appears on the Swiss list of sanctioned Russians - having no listed activity as a businessman on his bank documents.

At the time, the musician told the New York Time that he was certainly not a businessman and did not himself own millions, according to the indictment.

Roldugin was among scores of members of Putin's inner circle sanctioned by the West, including Switzerland, after Russia launched its invasion of Ukraine in 2022.

Reuters has approached his representatives for comment.

The case highlights how people like Roldugin were used as "strawmen" - a way to the hide true owners of the money, the indictment said.

There is little trace of Putin's assets.

"It is well known that Russian President Putin officially only has an income of 100,000 Swiss francs, and is not wealthy, but in fact has enormous assets which are managed by persons close to him," the indictment said.

Reuters has asked the Kremlin for comment on Putin's relationship with Roldugin and about his own wealth and assets.

Putin has in the past said that Roldugin is a friend, a brilliant musician and benefactor who has honestly earned some money from a minority stake in a Russian company.

The Kremlin has previously dismissed any suggestion that Roldugin's funds are linked to the Russian leader as anti-Russian "Putinophobia". Putin's finances are a matter of public record, says the Kremlin, saying he has regularly declared his assets and salary to Russian voters.

GODFATHER

The bankers in the case did not carry out sufficient checks to see if Roldugin was the true owner of the assets in question, the indictment said.

"At the time of the opening of the account it was reported in various articles.... that Sergey Roldugin was a close friend of the Russian President Vladimir Putin and godfather of his daughter," the indictment said.

Other red flags were ignored, and the defendants did not attempt to clarify the plausibility of Roldugin being the real owner of the assets, or the money's origin, the indictment said.

In the bank's documents, only Roldugin's professional activity as a musician was listed, making his ownership and involvement "in no way plausible", the court documents said.

In Switzerland, banks are obliged to reject or terminate business relationships if there are doubts about the identity of the contracting party.

Both accounts were closed in September 2016.

Roldugin has already been targeted by U.S. sanctions following Russia's invasion of Ukraine. The U.S. Treasury Department has described him as part of a system that manages Putin's offshore wealth.

He has also been sanctioned in Switzerland, whose government referred to him as "Putin's wallet" in its list of blocked people.

The prosecutor is seeking suspended sentences of seven months for each of the bankers. The trial is expected to last one day.