TV Tokyo manager Hironari Mori said more than 700 mainly schoolchildren were rushed to hospitals after watching the programme based on the video game "Pocket Monsters" on Tuesday night.
The Home Affairs Ministry said 208 people, aged from three upwards, including a man aged 58, were still in hospital with epilepsy-type symptoms more than 24 hours after the showing.
The blame was put on a scene depicting an explosion followed by five seconds of flashing red lights from the eyes of the most popular character, "Pikachu", a rat-like creature. Mori said the offending section passed inspection before broadcast, but in hindsight "we believe there may have been problems with presentation and production technique".
TV Tokyo imposed a health warning on future episodes, telling viewers that watching Tuesday's instalment of "Pocket Monsters could cause fainting and nausea.
The cartoon, shown since April, is the highest-rated programme in its time slot. Some local affiliates have already shelved the next episode. Japan's largest video rental chain, Culture Convenience Club Co Ltd, announced it was taking "Pocket Monsters" videos off shelves.
A spokesman for Nintendo, whose share price fell two percent, said the characters were the only link between its game and the cartoon. The game has been a huge success, selling seven million units since it was released in Japan in February 1996. It is scheduled to be released in the rest of the world next year.
A flickering television or computer screen can trigger a convulsion in anyone, especially if they have been sitting in front of it for a long time. The risk of a fit is related to the frequency of the flicker and the capacity of the retina of the eye to absorb it. If the retina absorbs a lot of flickering it sends impulses to the brain which can set off a seizure. Older TV sets with a mains flicker of 25 or 50 Hz carried a greater risk of triggering fits than modern sets with a higher frequency of 75 Hz.
The most susceptible people are those who have photosensitive epilepsy. About one in 130 people in Britain have epilepsy but only three to five per cent of those are photosensitive. A spokeswoman for the British Epilepsy Association said the number of children involved in the Japanese incident made it unlikely that they were all epilepsy sufferers. More probably they suffered a one-off convulsion as a result of the particular frequency of flashing lights.
The chances of a similar incident occurring in Britain are remote because the Independent Television Commission has rules limiting the use of flashing lights and flickering images. However, several incidents occurred with computer games in the early 1990s, and manufacturers now print warnings.Reuse content