In a policy back flip Tuesday, the Environment Ministry gave the green light to construction of new coal-fired power plants in exchange for power companies and the Ministry of Economy, Trade and Industry taking tougher measures to reduce global warming emissions.

The Environment Ministry has been wary of allowing such plants out of fear they could increase emissions. Announcing the policy reversal, Minister Tamayo Marukawa said officials will review each plan and "check whether it is consistent with the government's targets."

The decision came after Marukawa met with METI chief Motoo Hayashi on Monday night. During the meeting, Hayashi promised to introduce harsher standards on utilities to reduce greenhouse gas.

"Because the industry minister himself said (the system) will be operated properly, I understand that its viability has been ensured," Marukawa said at a news conference.

The Environment Ministry and METI will request all utilities to report how much carbon dioxide they have emitted in generating electricity after the Japanese power market is fully liberalized in April.

METI will also set standards for coal-fired power generation efficiency while requiring utilities to bring the ratio of renewable energy and nuclear power combined to at least 44 percent. It will issue instructions or recommendations if it finds the utilities' efforts are insufficient.

World Wildlife Fund Japan issued a statement opposing the move, saying it could result in coal-fired power plants operating into the latter half of this century while impeding the country's counter-emission measures for an extensive period.

"Japan should be at a stage where it strengthens measures against global warming," the statement said, while noting that coal is the highest carbon dioxide emitting fossil fuel.

"Tolerating the increase of coal-fired plants gives the wrong message to society, (it says) that it is still OK to use coal," WWF Japan said.