TOKYO (AP) The recent craze for hydrogen beer is at the heart of a three way lawsuit between unemployed stockbroker Toshira Otoma, the Tike-Take karaoke bar and the Asaka Beer Corporation. Mr Otoma is suing the bar and the brewery for selling toxic substances and is claiming damages for grievous bodily harm leading to the loss of his job. The bar is countersuing for defamation and loss of customers.

The Asaka Beer corporation brews "Suiso" brand beer, where the carbon dioxide normally used to add fizz has been replaced by the more environmentally friendly hydrogen gas. A side effect of this has made the beer extremely popular at karaoke sing-along bars and discotheques.

Hydrogen, like helium, is a gas lighter than air. Because hydrogen molecules are lighter than air, sound waves are transmitted more rapidly; individuals whose lungs are filled with the nontoxic gas can speak with an uncharacteristically high voice. Exploiting this quirk of physics, chic urbanites can now sing soprano parts on karaoke sing-along machines after consuming a big gulp of Suiso beer.

The flammable nature of hydrogen has also become another selling point, even though Asaka has not acknowledged that this was a deliberate marketing ploy.

It has inspired a new fashion of blowing flames from one's mouth using a cigarette as an ignition source. Many new karaoke videos feature singers shooting blue flames in slow motion, while flame contests take place in pubs everywhere. "Mr Otoma has no-one to blame but himself. If he had not become drunk and disorderly, none of this would have happened. Our security guards undergo the most careful screening and training before they are allowed to deal with customers" said Mr Takashi Nomura, Manager of the Tike-Take bar.

"Mr Otoma drank fifteen bottles of hydrogen beer in order to maximise the size of the flames he could belch during the contest. He catapulted balls of fire across the room that Gojira would be proud of, but this was not enough to win him first prize since the judgement is made on the quality of the flames and that of the singing, and after fifteen bottles of lager he was badly out of tune."

"He took exception to the result and hurled blue fireballs at the judge, singeing the front of Mrs Mifune's hair, entirely removing her eyebrows and lashes, and ruining the clothes of two nearby customers. None of these people have returned to my bar. When our security staff approached he turned his attentions to them, making it almost impossible to approach him. Our head bouncer had no choice but to hurl himself at Mr Otoma's knees, knocking his legs from under him."

"The laws of physics are not to be disobeyed, and the force that propelled Mr Otoma's legs backwards also pivoted around his centre of gravity and moved his upper body forward with equal velocity. It was his own fault he had his mouth open for the next belch, his own fault he held a lighted cigarette in front of it and it is own fault he swallowed that cigarette."

"The Tike-Take bar takes no responsibility for the subsequent internal combustion, rupture of his stomach lining, nor the third degree burns to his oesophagus, larynx and sinuses as the exploding gases forced their way out of his body. His consequential muteness and loss of employment are his own fault."

Mr Otoma was unavailable for comment.