Updated

A Danish newspaper says a whistleblower warned the management of Denmark's biggest bank in 2013 that family members of Russian President Vladimir Putin and Russia's spy agency were using its Estonian bank branch for money laundering.

Denmark's Berlingske daily says Tuesday the leaked internal report indicated that the Danske Bank leadership knew "of far more serious conditions than previously stated."

The paper adds that Danske Bank in 2013 shut down 20 Russian customer accounts following a whistleblower report alleging that its Estonian branch possibly had been involved in illegal activity. The clients' identities were kept secret at the time.

The paper shared details of the scheme with a group of anti-corruption reporters, among others.

There was no immediate comment from Danske Bank.