Tokyo:
Confirmation that radioactive materials have leaked into seawater around Japan's crippled Fukushima reactor sent fish sales plummeting in Tokyo on Wednesday.
Demand for seafood has been falling since the accident, but the first official reports of contamination drove even more shoppers away from Tokyo's biggest fish market.
Fukushima's crucial cooling system was knocked out during the March 11 earthquake and tsunami that devastated Japan's northeast coast.
The Health Ministry ordered officials to increase the monitoring of seawater and seafood after elevated levels of radioactive iodine and caesium were found in ocean water near the complex.
On Monday an official from Japan's Nuclear Industrial Safety Agency (NISA) admitted checks had not been carried out on the surrounding ocean, despite fire-fighters pouring tons of seawater onto the reactors and nuclear fuel cooling pools.
"As far as seeing where that water goes after that, we are not monitoring or even doing proper visual checks," Hidehiko Nishiyama, NISA's deputy director-general said.
A specialised research vessel has been dispatched to collect and analyse samples of seawater.
Health officials emphasise the levels of contamination detected so far pose no immediate risk to health, and a ban on seafood from the area is not yet necessary.
A fishmonger inside Tsukiji Fish Market complained about the lack of customers and urged the government to tackle the issue quickly.
Shoppers are also worried about contamination. One shopper said he wanted to eat fish before contamination rises.