A chess queen caught on CCTV apparently poisoning a rival's board with mercury has escaped any charges after prosecutors dropped the case.

Chilling footage shows Russian chess pro-Amina Abakarova, 40, spreading what was believed to be the toxic chemical where her rival was due to sit for a tournament match.

Later, her opponent, Umayganat Osmanova, 30, collapsed while playing in the Dagestan Chess Championship in southern Russia last August.

In the original security footage, Abakarova was seen walking into the tournament room and looking around furtively before approaching her rival's board.

Then she appeared to brush a dark grey powder, which was understood to be mercury, onto the board and smeared it around with a chess piece.

Abakarova was arrested after doctors discovered Umayganat had been poisoned and a review of the tournament venue's security footage discovered Abakarova's tampering.

But now, it has emerged that Abakarova has never been punished, formally charged, or even been to court after investigators determined the victim's injuries were not serious enough.

Because she did not suffer any lasting consequences to her health after the poisoning, Abakarova has been told that the case has been shelved, Russian media reported on December 5.

Furious Umayganat said: 'I was sent for a medical examination, and since there were no consequences or physical injuries, [the case] was not initiated.

'Obviously, there wouldn't be physical injuries in this case; the case was about the fact I inhaled a toxic substance.'

She claimed: 'Everywhere I went they turned me away. We sent submissions to the prosecutor's office and then to the Investigative Committee but they keep sending us around in circles.

'They didn't even call me to a court hearing – she [Abakarova] was just let free.'

Now, Umayganat is determined to have a rematch with her rival in a private prosecution or a civil damages case.

She added: 'The person who did this to me, was not even issued an administrative fine.'