A Latvian chess player allegedly posted pornographic images to top young female players, most of them Russian and several underage, in a decade-long harassment campaign, according to an investigation by independent Russian media.

The claims have shone a light on what the mother of one victim described as a “toxic atmosphere” in the male-dominated sport.

Fifteen women and girls said they had been receiving the disturbing packages, some of which included used condoms, since at least 2009.

However, the scandal was kept under wraps for years until the suspect mailed several letters to the hotel in Latvia where several women players were staying for an international tournament last November. A police investigation was then opened.

Meduza, the Russian news site, reported claims that Andrejs Strebkovs, a 40-year-old Latvian with the title of International Master, one rung below Grandmaster, was the sender of the packages. The Telegraph was unable to reach him for comment.

‘There are lots of crazy people around’

One of the women alleged to have received the vulgar letters is Valentina Gunina, currently ranked as the world’s ninth strongest female chess player.

“There was a condom inside. A used one. I had no idea anyone else was getting them. I thought it was just me,” the 33-year-old chess grandmaster told The Telegraph as she recalled receiving her first letter mailed to her chess school in Moscow when she was in her early 20s.

“There are lots of crazy people around.”

Most of the female players never mentioned the letters to anyone but their families. Some of the women were repeatedly targeted and received letters to their home address, Meduza reported.

Ms Gunina told The Telegraph that she only started worrying when she got a letter at the tournament in Latvia last year.

She said: “I never received any letters to my home address – only to my school, which made me feel safe. This time it triggered me because it was me again and many more girls.”

A former chess player who saw the letters at the tournament told The Telegraph: “This is the stuff from books about maniacs. There is no other way of putting it”.

Fide, the international governing body for chess, said it took action as soon as it discovered the letters.

It said: “We reported it to the police right away on behalf of the players, to minimise distractions to them. We can confirm that the Latvian Police took it seriously and it is actively investigating.”

Women in the sport face ‘toxic atmosphere’

Several people, including the mother of 17-year-old Bibisara Assaubayeva, the youngest woman to win the Women’s Blitz World Championship, earlier filed complaints with police in Russia, but the investigation was never formally opened.

Many female players, including Ms Gunina, dismissed the harassment as the work of one “mentally unstable man”. However, Liana Tanzharikova, the mother of Ms Assaubayeva, said that the letters pointed to a toxic atmosphere for women in the sport.

The chess world has long been known for being unwelcoming to women, as explored in The Queen’s Gambit, the hit Netflix show which drew on real events.

A former chess player who asked to be unnamed told The Telegraph that many male players often do not hide their aversion for the few female players who compete at their level.

She said: “There is a lot of prejudice coming from boys and men. They often want to show off their superiority.”

Acquaintances described Mr Strebkovs as a talented player who was a loner.