For most of the past 30 years the American chess genius Bobby Fischer has lived in exile following his epic defeat of the Russian world champion Boris Spassky in a contest billed as the battle of the superpowers.

But now it has emerged that Fischer may have made an eccentric return to global chess by anonymously taking on some of today's best players on the internet.

The British grandmaster Nigel Short said yesterday he was "99% sure" that he had played about 50 games of three-minute "blitz" chess against Fischer on the net - and been comprehensively beaten by him.

Fischer disappeared from public view after beating Spassky in Reykjavik, Iceland, in 1972, a match which was almost as symbolically important to the US as the race to the moon. He was briefly drawn out of obscurity for a 20th anniversary rematch by the lure of a £2m prize.

But then little more was heard of the man who won the American championship aged 14 - until rumours began circulating in the chess world that Fischer was back, playing chess on the internet.

Short, the former official challenger to ex-world champion Garry Kasparov, said he was sceptical when a young Greek grandmaster told him he had played blitz chess with Fischer though the Internet Chess Club (ICC), a cyberspace meeting place for some of the world's top players.

However, while logged on to the ICC a few weeks later Short said he was approached by a man claiming to be an intermediary who asked if he would play against a "very strong chess player".

Code word



The intermediary said the mystery player wished to remain anonymous but would give Short a code word so that he knew he was playing against the right person.

In October last year Short was again logged on to the ICC when a player approached Short using the code word. He said: "My heart jumped. Could this be Bobby Fischer?"

The mystery opponent asked Short to log off and back on as a unnamed guest rather than under his own identity. This meant that anyone else watching the game's progress on the internet would have no idea who was playing and that the game would not be recorded.

Short said the first three-minute game began with his opponent making some "totally absurd" opening moves, including shifting all his pawns forward one square, to severely weaken his position.

Practical joke



The British player thought he had been the victim of a practical joke. But from this poor position Short said there followed "moves of extraordinary power". In the first game he was "totally crushed".

Though his opponent's openings became increasingly "cocky" - in one he immediately exposed his king to attack - Short went on to lose eight games in a row.

In all, Short said he was to play the mystery opponent some 50 times and did not come close to winning half the games, though he still regarded as one of the best players in the world and is strong enough to have drawn a series of blitz games against Kasparov.

When the British grandmaster ran short of time, the opponent would add seconds to his clock so that he would not beat him just because he was out of time.

It would be extraordinary if it was proved that Fischer, regarded by many as the greatest chess player ever, had made a secret internet comeback and, at 58, was still sharp enough to easily beat players of Mr Short's class.

After beating Spassky during the cold war Fischer made a guest appearance on the Bob Hope show, played a private match with President Ferdinand Marcos of the Philippines and then vanished as sponsors lined up to make him rich.

He was stripped of his world title when he declined to defend it and since then is rumoured to have spent time in Japan. He is now thought to live for most of the time in Budapest, his privacy guarded by a circle of chess cronies.

Two years ago, out of the blue, he appeared on a Hungarian radio station, explaining that he lived in the city because he liked the thermal baths. More seriously, he went on to allege that he was the victim of a Jewish world conspir acy and made claims which led to the presenter cutting him off.

The Fischer legend has made him a favourite for hoaxers. The ICC believes there are at least three Fischer hoaxers on the internet, which is an increasingly popular forum for chess players. One is thought to be a mischievous grandmas ter, the other two amateurs who use computers. But Short became convinced his opponent was the real Fischer as they chatted about chess and chess history.

Short did not ask him directly if he was Fischer but tried to probe him indirectly. He once asked if he knew a certain obscure Mexican player. His opponent replied "Siegen 1970", the place and year of a game between Fischer and the Mexican.

On another occasion Short asked his opponent who was the strongest blitz chess player he had ever played. The opponent replied: "If I am who you think I am, I would answer Mikhail Tal." Tal is a former champion who resoundingly beat Fischer at speed chess.

When Short told Boris Spassky of the games, the former world champion said he believed it was "highly probable" that he had indeed been playing Fischer.

Short's conclusions about his opponent are startling. He said: "Fischer is in my opinion a much stronger speed chess player than Kasparov, which is incredible when one considers that at 58 he is virtually a geriatric in terms of the modern professional chess game."

The British player said he decided to reveal the games - even though it will probably mean that the two will never play again - in an article in yesterday's Sunday Telegraph because the rumour that Fischer was playing on the internet had begun to gather strength and would have emerged anyway.

He said he would not publish details of the games as Fischer would be furious. But he concluded: "To me they are what an undiscovered symphony would be to a music lover."

 The demands of Fischer and Spassky have become legendary. During their epic match, Spassky insisted that Fischer's chair be stripped down and searched, believing that the American was concealing a bug which was sapping his energy. Nothing was found. For his part, Fischer made extraordinarily precise demands about the specification of the chess pieces he would use and about the size and shape of the chairs he would sit in to play. When it came to defending his world championship he came up with 179 conditions and then decided not to play.

 Computer technology plays an increasingly important role in the modern game. Yesterday afternoon no fewer than 1,429 players including five grandmasters were playing through the Internet Chess Club (ICC), where Short believes he encountered Fischer. Later this year a program called Deep Fritz which can make up to 6m calculations a second will take on the current world champion Vladimir Kramnik. Garry Kasparov's defeat by the computer Deep Blue in 1997 is believed to have been a contributory factor to his loss of the world championship to Kramnik.

 Some of the finest players in the world are behind bars. Claude Bloodgood, for instance, is an American grandmaster serving a life sentence for beating and strangling his mother. Because he must post each move to his opponents around the world and wait for a reply, an average game can last eight months.

 Governments have long used chess players. The British chess team was ordered back from a tournament in Argentina at the outbreak of the second world war so that they could work as code-breakers. Chess players were among the team which cracked the Enigma code. The Japanese confiscated chess books from prisoners of war, thinking they were military codes. Some probably were.

 Chess is a surprisingly physical game. Kasparov has a team of trainers who keep his body as well as his mind at its peak. While preparing to take on Nigel Short in 1993 he had a training camp set up much like a boxer's on the Adriatic coast. During a 10-match game in 1990 Nigel Short shed about half a stone.