Japan's efforts to cut carbon dioxide emissions may be compromised as more coal-fired thermal power stations, which emit large amounts of the greenhouse gas, are being built, prompting the Environment Ministry to dig in its heels over the need to introduce an environment tax.

These power stations are attractive for utilities because coal is cheaper than oil and natural gas. And the recent liberalization of the power industry makes it easier for newcomers to the market to build them.

But the flip side of these advantages is that they are hampering the government's push to achieve its greenhouse gas reduction targets under the 1997 Kyoto Protocol, which aims to curb global warming.