Russian grandmaster Garry Kasparov has been warned by the World Chess Federation (FIDE) that he may be referred to its Ethics Commission after he announced plans for a comeback.
From 1986 until his retirement in 2005, Kasparov was ranked world number one for 225 out of 228 months.
Last week, Kasparov revealed he planned to resume his career by taking part in the Grand Chess Tour at St Louis, scheduled to take place between August 13 and 20.
But Kirsan Ilyumzhinov, President of FIDE, has claimed that Kasparov must first be cleared to compete.
The former world chess champion was disqualified for two years for alleged corruption and vote buying at the 2014 FIDE Presidential election at Tromso in Norway.
Kasparov had lost the election to Ilyumzhinov, who is also Russian, by 110 votes to 61.
A few days before the election took place, the New York Times Magazine had published a report on the campaign which Included information about an alleged leaked contract between Kasparov and former FIDE secretary general Ignatius Leong.
It was alleged that Kasparov had offered to pay the Singaporean $500,000 (£388,000/€439,000) and the Asean Chess Academy $250,000 (£194,000/€219,000) a year for four years to the Asean Chess Academy in return for 11 votes.
Both were banned in September 2015 for two years following a hearing of the FIDE Ethics Commission.
Kasparov has played friendly and exhibition matches since his retirement but the event in St Louis would mark his first formal competition for more than a decade.
The 54-year-old is now officially a Croatian citizen and lives in New York City.
in 2008 he had announced he planned to run against Vladimir Putin in the Russian Presidential elections but was unable to get enough support for his campaign.