An American chess grandmaster had multiple drugs in his system when he died, a fresh toxicology report has revealed.

The chess world was rocked in October last year when Daniel Naroditsky was found unconscious at home on a sofa by his friends, in Charlotte, North Carolina. He was 29 years old.

Now a new toxicology report has found the former child prodigy had methamphetamine, amphetamine, 7-hydroxymitragynine and mitragynine in his system, Sky's US partner network NBC News reports.

Whilst methamphetamine and amphetamine are synthetic stimulants, 7-hydroxymitragynine and mitragynine are major psychoactive ingredients found in Kratom - a southeast Asian plant that can be used as a stimulant.

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However, the plant can "lead to psychotic symptoms, and psychological and physiological dependence," the American Drug Enforcement Administration warned.

One of his friends who found him, fellow chess grandmaster Oleksandr Bortnyk, later said Mr Naroditsky had been distraught after one of his chess heroes, former world chess champion Vladimir Kramnik, accused him of cheating.

Kramnik, 50, told NBC News that he has been the "subject of a bullying and slandering PR campaign", as well as ongoing threats to him and his family following Naroditsky's death.

The World Chess Federation (known as FIDE) said Kramnik could be banned from the organisation entirely following Naroditsky's death.

FIDE did not immediately respond to a request for comment, NBC reported.