Hundreds of water tanks are to be sent to Japan's crippled Fukushima nuclear plant to hold thousands of tons of water contaminated in the effort to keep its reactors cool, the operator said Sunday.

Plant operator Tokyo Electric Power Co. (TEPCO) has sourced 370 tanks with a total capacity for more than 40,000 tons of radioactive water, a company spokeswoman said.

"Two of the tanks got on the way to the plant late Saturday," said TEPCO spokeswoman Ai Tanaka, adding that they would reach the site in two days or so. "It will be in mid-August that all the 370 tanks will get to the plant."

A massive 9.0-magnitude earthquake and monster tsunami knocked out cooling systems at the plant on the Pacific coast on March 11.

In a stop-gap measure to contain the emergency at the plant, workers have been pouring massive amounts of water onto reactors where fuel rods are reported to have melted, and topped up pools for spent fuel rods.