Japan's Nuclear and Industrial Safety Agency said Wednesday that seawater near the crippled Fukushima Daiichi nuclear plant's No.1 reactor contained radioactive iodine at 3,355 times the legal limit.

Deputy Director-General of the agency, Hidehiko Nishiyama, said that as there was no fishing in the region the effects on the local residents would be minimal.

"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.

But whilst the nuclear safety agency said on Tuesday that radioactive water from the quake and tsunami damaged Fukushima Daiichi nuclear power plant had not been confirmed to have leaked into the Pacific Ocean from the plant's underground drainage system, the agency did confirm that radioactive iodine-131 more than 1,000 times above the allowable level was detected in a seawater sample taken around 1.5 kilometers north of the drainage outlets of the plant's four most troubled reactors.

A reading of 3,355 times the legal limit, as was detected Wednesday, suggests the problem is mounting.

The plant's operator, Tokyo Electric Power Co. (TEPCO) has been working to remove contaminated water from some of the reactor's basements and pump it into turbine condensers for storage.

Japan's nuclear safety agency confirmed on Wednesday that efforts by the plant's operator to remove contaminated water had been somewhat successful as the level of flooded water had halved in the six-reactor complex's No. 1 unit basement, according to the agency.

Meanwhile, Chief Cabinet Secretary Yukio Edano told a news conference Wednesday that the government and nuclear experts are discussing "every possibility" to bring the plant under control.

Edano did not deny that some speculative measures floating around press circles had also been taken into account.

Such measures include covering reactors of the plant with special cloth to reduce the amount of radioactive particles flying away from the facility and using a big tanker to collect the contaminated water.