(Adds details and background on Panama Papers)
ZURICH, Feb 1 (Reuters) - Switzerland's Financial Market Supervisory Authority on Thursday banned Gazprombank Switzerland from accepting new private clients until further notice after finding serious shortcomings in its efforts to curb money laundering.
The decision wraps up FINMA's investigation into possible wrongdoing in Switzerland, the world's foremost centre for offshore wealth, in connection with the so-called Panama Papers.
The documents, leaked to a German newspaper, in 2016 detailed how the rich and powerful used offshore corporations to hide money and potentially evade taxes.
FINMA said on Thursday it had looked into a total of 30 Swiss banks related to information revealed in the 11.5 million leaked documents from Panamanian law firm Mossack Fonseca.
"In-depth investigations were carried out at around 20 banks," the financial authority said. "Where necessary, FINMA required banks to take action to improve their anti-money laundering processes."
FINMA's investigation found the Swiss subsidiary of Russian state-owned Gazprombank to be in serious breach of anti-money laundering due diligence requirements between 2006 and 2016.
"The bank failed to carry out adequate economic background clarifications into business relationships and transactions with increased money laundering risks," FINMA said in a statement. "No new relationships with private clients may be accepted and existing relationships must be strictly monitored."
Gazprombank belongs to Kremlin-controlled gas giant Gazprom .
Gazprombank Switzerland said it accepted FINMA's decision. It noted the measures related exclusively to its business with private clients, adding it is primarily engaged in corporate banking and conducts only limited business with private individuals.
"The bank will pursue its ongoing efforts to further enhance its organisation, risk management and compliance functions," it said.
Germany weeks ago said it had found no evidence of substantial breaches of money laundering rules by 11 of its banks named in the Panama Papers.
In a separate crackdown on money laundering, FINMA ordered PKB Privatbank SA Lugano to turn over 1.3 million Swiss francs ($1.40 million) in unlawfully generated profits from business linked to scandal-plagued Brazilian groups Petrobras and Odebrecht. (Reporting by Brenna Hughes Neghaiwi; Editing by Michael Shields)