TOKYO -- Seawater near the crippled Fukushima Daiichi nuclear complex's No.1 reactor contained radioactive iodine at 3,355 times the legal limit, Japan's Nuclear and Industrial Safety Agency said on Wednesday.

Hidehiko Nishiyama, deputy director-general of the agency, played down the potential effects of the radioactive seawater as residents in the area had been evacuated and there was no fishing activity in the region.

"Iodine 131 has a half-life of eight days, and even considering its concentration in marine life, it will have deteriorated considerably by the time it reaches people," Nishiyama told a news conference.