A German publisher said Wednesday that it will stop selling books about Russian President Vladimir Putin written by a prestigious journalist, after it emerged that he allegedly received at least 600,000 euros ($651,000) in payments linked to Russian sources.

Publisher Hoffmann und Campe said in a statement that it will stop selling two books about Putin by German journalist Hubert Seipel following reports by the weekly Der Spiegel and public television ZDF, adding that it was previously unaware of the allegations.

According to reports on Tuesday, Seipel was receiving funds indirectly linked to a sanctioned Russian oligarch to portray a favorable image of Putin in his books.

Public television NDR, which had produced a documentary with Seipel in 2012 about Putin and aired his interviews with the Russian president, also said it was considering legal action against the reporter.

The allegations, published by international media outlets such as The Guardian, are based on information that emerged from Cyprus Confidential financial files leaked to the International Consortium of Investigative Journalists.

The two books are “Putin’s Power” (2021) and “Putin. Interior views of a power” (2015), the editor said.

Der Spiegel and ZDF reported that, in response to the allegations, Seipel denied having received money from third parties for films or television interviews.

At the same time, according to Der Spiegel, Seipel is said to acknowledge receiving support for future books.

NDR said in a statement that “Seipel acknowledged to NDR that he had received money from Alexey Mordashov through two ‘endorsement contracts’ in 2013 and 2018 and explained that it was for two book projects.”

Mordashov, who is believed to have close ties to Putin, is one of many Russian oligarchs sanctioned by the United States, Britain and the European Union following Russia’s invasion of Ukraine in February 2022.

NDR said that the journalist had not disclosed these contacts during his collaboration and that “the broadcaster considers this a significant conflict of interest that raises questions about Seipel’s journalistic independence.”