Outraged by the loss of his privileges and by accusations of cheating, Vladimir Kramnik, the Classical World Champion, forfeited the fifth game in the series against Veselin Topalov, allowing his Bulgarian rival to narrow the gap.

Before yesterday’s no-show, Kramnik was leading 3-1 in the 12-match series, played for the prestige of the undisputed world title in chess and an equal share of the $1 million (£534,000) prize.

However, on Thursday the losing Topalov camp opened a new front of the battle by claiming that the video surveillance from the rest rooms had revealed that Kramnik had been visiting the lavatory frequently.

The Bulgarian’s officials described the Russian’s lavatory visits as “strange and suspicious”, implying that Kramnik had been receiving computerised help.

Experts dismissed this as unlikely, not least because of Kramnik’s own blunder in game 2, which could have cost him the game. Indeed, the Russian grandmaster’s massive lead could be safely ascribed to Topalov’s own errors rather than Kramnik’s genius.

The Topalov team demanded that the lavatories in their own rest areas be closed, forcing the protagonists to share the public facilities, in the company of an assistant arbiter. Topalov simultaneously issued a press release stating that he would no longer shake hands with his bitter rival, and threatened to abandon the world championship match being staged.

The Appeals Committee decided in Topalov’s favour, ruling that the lavatories in the rest areas should be sealed, and the players should use a public toilet which would be reserved for the two of them.

This would be unprecedented in a modern world chess championship contest. It is a recognised convention that when it is not your move you can walk away from the board, but not leave the building.

Kramnik turned up at the venue as scheduled yesterday, but refused to go to the board. “I am ready to continue the match and play the 5th game,” he said, “on the conditions that were accepted prior to the start of the match. My dignity does not allow me to stand this situation. Now I am going to return to my cottage and rest.” With that he left the building.

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