A prominent Swiss asset manager is facing extradition to the US after being arrested while holidaying in Italy on charges that he helped American clients with $20bn of assets to evade US taxes during his previous job at UBS.

Police in Bologna said Raoul Weil was arrested early on Saturday after he registered at a hotel and his name appeared on a police list of international arrest warrants. Mr Weil was transferred to Bologna’s prison where the next step would be for the US to request his extradition, police said.

Mr Weil had been working openly in Switzerland’s asset management industry as chief executive of Reuss Private Group, which handles assets of more than SFr4bn ($4.4bn). Reuss, based in the Swiss canton of Schwyz, said he had been on a “private” visit to Italy.