Poison terror in the subway

In the first terrorist attack of its kind, seven people died and more than 4,700 were poisoned yesterday when nerve gas fumes spread through Tokyo's subway system at the height of the rush-hour. Last night, more than 18 hours after the tragedy, there was no clue as to the identity or motive of the terrorists.

Japanese authorities said the nerve gas sarin had been deliberately planted in parcels in at least five subway carriages and up to 16 stations on three lines. Some passengers reported seeing a masked man. Others said they saw a man leaving packages the size of lunchboxes inside carriages or on platforms.

All but one of the dead were passengers on underground trains. The seventh was a station official who picked up a suspect package. In central Tokyo, passengers fainted, vomited and went into convulsions as fumes spread. Some foamed at the mouth and bled from the nose.

Outside more than a dozen stations, people lay on pavements as doctors and ambulance staff tried to revive them. Hospitals were overwhelmed by hundreds of patients suffering the unfamiliar symptoms. Late last night, hundreds of the 3,200 who sought treatment were still in hospital.

Sarin was developed by German scientists in the Second World War. Twenty times as deadly as potassium cyanide, it cripples the nervous system and can kill in minutes. A few droplets absorbed through the skin or inhaled cause impaired vision, vomiting, headaches and respiratory problems. Although the gas is a combination of two harmless substances, scientists said it had to be handled extremely carefully in the final stage of manufacture.

The authorities refused to discuss suspects, either political groups or Aum Shinri Kyo, a religious cult previously accused of making sarin at a central Japan commune. The cult yesterday denied involvement in the Tokyo attacks, and threatened to sue any accusers.

Yesterday's tragedy echoed an unresolved case last year, when sarin seeped through the windows of homes in the city of Matsumoto one evening, killing eight people and poisoning 200. No one has been charged, and police refused yesterday to speculate whether there was a link.

Two incidents this month may have been rehearsals for yesterday's attack. On 15 March, three cases were found at a Tokyo underground station, each containing three tanks with an unknown liquid, small motorised fans, a vent, and a battery. One was giving off a vapour. Ten days before that, 19 people were taken to hospital after they inhaled mysterious fumes on a train in Yokohama and suffering eye and respiratory pain.

Yesterday's attacks were so indiscriminate as to obscure any motive. Poison gas claimed victims in stations near the Diet, the imperial palace, the US embassy and Tokyo University, but working-class districts were also hit.

If a political group was responsible, the main suspect would be the Japan Red Army - former student radicals who carried out a series of attacks and airline hijackings in the Seventies. It is now thought, however, to have dwindled to a small band of lonely, middle-aged guerrillas in Lebanon.

In the wake of Tokyo's chaos and panic, authorities in other Japanese cities were put on alert. The attacks create a security nightmare for public transport systems. New York and Hong Kong were among citiesexercising extra vigilance.