Broadcaster NDR launches investigation after Hubert Seipel admits receiving support for work on two books on Russian leader

A German publisher has announced a stop to the sale of books authored by a leading journalist and Russia expert after an investigation showed he had received at least €600,000 (£522,000) in undisclosed offshore payments from companies linked to an oligarch close to Vladimir Putin.

Hubert Seipel, an award-winning film-maker and author, admitted receiving support for his work on two books charting the Russian leader’s rise to power and offering portrayals described as sympathetic to him.