Japanese police poised to seize cult members

Japanese police investigating last month's nerve gas attack on the Tokyo subway appeared to be close to making arrests yesterday, as mysterious fumes were reported for the second time in two days in the city of Yokohama.

Investigators were preparing charges last night against the Aum Shinri Kyo religious group, widely believed to have manufactured the sarin gas which killed 12 commuters and injured 5,500 on 20 March. Yesterday 24 people were treated in Yokohama hospitals after a noxious smell was reported 200 metres from the site of a similar incident earlier in the week.

The fumes were reported in a department store opposite Yokohama's main station, where 700 people were affected by a strange smell on Wednesday. A group of schoolgirls complained of pain in their throats and eyes. "When I smelt it I started choking, and felt a pain in my eyes," said a young man who was with the girls. "It stung my nose and made me want to spit."

Within an hour the department store had been closed off, and those affected were taken to hospital, although none was expected to be detained. Police and firemen with breathing equipment searched the area, but last night no clues had been found to the nature of the fumes or their source.

At an emergency meeting in Tokyo, Yuko Sekiguchi, deputy general director of the National Police Agency, told regional chiefs to step up investigation of the recent terrorist incidents. "At home and abroad, people are voicing concern about Japan's domestic security," he said, in an unusually frank public statement.

"We must not shy away from our responsibility, but aim to solve the case as a whole. The investigation has reached a turning point: we have to tear down the thick walls surrounding the case and disclose the entire allegations."

According to the Yomiuri Shimbun newspaper, police have identified seven members of Aum Shinri Kyo's so-called "science and technology ministry", believed to have synthesised sarin at the cult's laboratory on the slopes of Mount Fuji. The chief of the "ministry" has appeared frequently on television in the past few weeks to deny the cult's involvement in the gas attacks, claiming that tons of chemical ingredients recovered from Aum premises were for the manufacture of fertilisers and ceramics. The Aum guru, Shoko Asahara, has not been seen in public since before the sarin attack.

The sister of a man alleged to have been kidnapped by Aum appeared on television last night, describing her ordeal at the hands of the sect. Aiko Nishina, 62, joined the sect after being told that she would be able to make contact with the spirit of her dead husband. She donated 60m yen (£470,000) at the behest of senior members, including Mr Asahara. In return, she underwent initiations involving the drinking of a fluid, apparently a narcotic.

On 24 February she escaped from the group's Tokyo headquarters to the home of her brother, Kiyoshi Kariya. Three days later, Aum members visited Mr Kariya and an argument ensued when he refused to tell them where she was. On 27 February, he was seen being bundled into a van by unidentified men; he has not been seen since.