Four bankers who allowed a friend of Vladimir Putin to deposit huge sums in Swiss banks have been found guilty of lacking due diligence.

The former executives at the Zurich branch of Russia's Gazprombank were given seven-month suspension sentences for helping musician Sergei Roldugin, nicknamed "Putin's wallet".

Mr Roldugin reportedly paid in $50m (£42m) between 2014 and 2016.

He gave no credible explanation of where the money had come from.

Under Swiss law, banks are required to reject or close accounts if they have doubts about the account holder or the source of the money. Mr Roldugin, a cellist, is godfather to President Putin's eldest daughter, Maria.

Three of the convicted bankers are Russian and one is Swiss.

The men, who cannot be identified under Swiss reporting restrictions, said they would appeal against the Swiss court's decision.