Japan will accelerate efforts to prevent more radioactive groundwater from seeping into the ocean at the crippled Fukushima nuclear plant, government officials say, as critics slam its operator's handling of the issue.
Prime Minister Shinzo Abe is expected to order his government to hand over public money to help foot the bill for ramped-up measures, the first time that Tokyo has committed extra funds to deal with the growing problem.
"Taking measures to contain contaminated water is an important part of the process towards decommissioning (the site)," Chief Cabinet Secretary Yoshihide Suga, the government's top spokesman, told reporters on Wednesday.
"The prime minister is expected to instruct the industry minister to take measures as soon as possible."
In May, Tokyo ordered plant operator Tokyo Electric Power (TEPCO) to build new barriers around the plant's reactors to contain toxic water that is used to keep the reactors cool, a measure that could cost up to Y40 billion ($A456.9 million).