The companies had initially planned to start construction of the power station this month but have not made a formal decision to go ahead with the project, Takahito Hirota, a spokesman at Kansai Electric told Reuters on Thursday. The plant is proposed for near the city of Akita, about 450 km (280 miles) north of Tokyo.

"We have delayed construction of the power plant in Akita from August as was stated in our environmental impact assessment document and no new construction schedule has been set," Hirota said, adding a final decision on the project has not been made.

Coal-fired power generation is a major contributor to carbon and other emissions that scientists say are contributing to global warming, which is causing heat waves, rising sea levels, droughts and other extreme weather event.

Japan's government earlier this year said the country would aim to be carbon-neutral as soon as possible after 2050.

The country is one of the few major industrialized economies that is planning a major expansion of coal-fired power generation. Japan is making that decision after the Fukushima disaster in 2011 that led to the shutdown of most of the country's nuclear reactors.

For a graphic on Japan's energy mix:



But many of these plans are being shelved amid local opposition, while the country's environment ministry has taken a tougher stance on environmental approvals.

Kansai Electric and Marubeni have given up access rights to the electricity grid to supply power from the planned Akita coal station, two industry sources told Reuters, with one of them saying this indicates that the companies have cancelled their plans for the project.

Hirota declined to comment on the grid access issue, while a Marubeni spokeswoman declined to comment on the project other than to say "we are continuing to carefully consider" the plans for building the station.

Japanese banks and trading houses, which have long backed the use of coal, have been tightening policies on financing coal power and mines in recent months.

Sumitomo Corp one of Japan's biggest trading houses, tightened its policies on coal this month.

The company will not invest in new coal-fired power plants or new thermal coal mine projects, it said in the latest Integrated Report issued last Friday.

For a graphic on Japan's thermal coal imports:



(Reporting by Yuka Obayashi and Aaron Sheldrick; additional reporting by Yuri Harada; editing by Christian Schmollinger)

By Yuka Obayashi and Aaron Sheldrick