Tokyo Metropolitan Government officials on Friday played down flooding beneath a proposed flagship food market in Toyosu as the result of heavy rain that will be pumped out or will seep away.

Later in the day, a team of Tokyo Metropolitan Assembly members from the Japanese Communist Party who investigated the flooding said they detected arsenic in the water they sampled but that its quantity was below the environmental standard.

The legal limit for arsenic in water is set at 0.01 mg per liter. The amount found in the JCP sample was 0.004 mg per liter, the assemblymen said, adding that no benzene was found.

The water is of concern because the market stands on land that was polluted with toxic chemicals during its previous life as an industrial site. If the flooding is groundwater that has welled up, it may have brought contaminants.

Initial testing by the JCP team had found the water was strongly alkaline, and the JCP asked a private research institute to further analyze the water.

In November, the complex was supposed to receive the fish and vegetable traders who currently operate at Tokyo's historic Tsukiji market. Tokyo Gov. Yuriko Koike has postponed the move indefinitely.

In a bid to dispel fears, officials on Friday took reporters to see the space, beneath one of three buildings that will serve as a seafood wholesalers' and fruit and vegetable wholesalers' market.

In some areas the water was observed to be about 20 cm deep.

The officials said the problem will be fixed when construction is completed in mid-October.

They rejected suggestions that the water may be toxic, saying the level of benzene in the soil is within national safety standards and poses no hazard to health.

Information from Kyodo added