German public broadcaster ARD announced in a statement posted on its website on Friday that the Russian authorities had declared invalid a visa application sought for Hajo Seppelt on the grounds that the journalist's name is on a list of people declared "persona non grata" in the country. No further explanation was provided by the Russian authorities.

Since 2009, Seppelt and the ARD have repeatedly uncovered and reported on doping scandals, including working with whistleblowers to expose systematic cheating in Russian track and field. The 55-year-old Berlin-based journalist has won a number of awards for his work on doping and efforts to cover it up.

'Unprecedented infringement of the freedom of the press'

"The ARD regards this as an unprecedented occurrence in the history of ARD sports journalism and with regard to reporting on major events such as the World Cup of football, an unprecedented infringement of the freedom of the press," the broadcaster said in its statement.

It added that not only is the free access of members of the media from all over the world usually a matter of course for major sporting events such as the World Cup or the Olympics, but that it is also one of the requirements that must be met before a country can be chosen to host such events.

The ARD's director of programming, Volker Herres, expressed dismay at the news and said he hoped the Russian authorities would rethink the decision.

RUSADA still suspended over WADA report

Russia's anti-doping agency, RUSADA, has been suspended since 2015 after a World Anti-Doping Agency (WADA) commissioned report revealed alleged widespread doping in the country.

A further report the following year by Canadian sports lawyer Richard McLaren found that more than 1,000 Russian competitors had been involved in a conspiracy to conceal positive drug tests over a period of five years and that football was among more than 30 sports involved.

Russia has repeatedly denied any state involvement in doping.

pfd/ (AP, Reuters, dpa)