The Group of Seven major developed countries began a two-day meeting of environment ministers Thursday in Berlin, with the utmost attention on whether they can set a specific time frame to phase out coal-fueled energy.

Germany, serving as the chair of G-7 meetings this year, has proposed that the ministers stipulate the goal of phasing out coal power generation by 2030 in a post-meeting joint statement, and other European countries and Canada have backed the idea, officials said.

But the Japanese government remains opposed to committing to a specific time frame, while the United States has compromised to aim for the goal "in the 2030s."

"Only Japan is saying such a goal should be deleted and is a little isolated," a Japanese government official said.

Still, there are uncertainties as Russia, a major fossil fuel exporter, launched its invasion of Ukraine more than three months ago.

The G-7 countries, also including Britain, France and Italy, have imposed sanctions on Russia since then and agreed to reduce their reliance on Russian energy imports.

The sanctions could derail efforts to cut greenhouse gas emissions as some energy importers may need to burn more coal.

Japanese Environment Minister Tsuyoshi Yamaguchi told reporters earlier this week in Tokyo, "We will cut the ratio of coal while introducing renewable energy as much as possible, rather than setting a specific time frame."

"We would like to seek their understanding on our efforts to eliminate inefficient coal-fired plants and shift to a system not emitting carbon dioxide," Yamaguchi said Tuesday, referring to cutting-edge technologies, such as carbon capture and reuse, which Japan intends to employ more in the future.

From Japan, Toshitaka Ooka, senior vice environment minister, and Kenichi Hosoda, senior vice industry minister, were slated to take part in the meeting on climate, environment and energy issues as their superiors, required to attend parliamentary sessions, could not make it.

Prior to the ministerial meeting in the German capital, due to conclude Friday, the International Energy Agency recommended that the G-7 lead the world in the transition toward steel and cement production with almost no emissions.

Heavy industry is responsible for more than 15 percent of coal use and about 10 percent of oil and gas use in the G-7 countries, the agency said.

The G-7 countries plus the European Union account for about 40 percent of the global economy, 30 percent of energy demand and 25 percent of energy system CO2 emissions, according to the IEA.

Related coverage:

G-7 ministers' draft statement contains coal power phaseout by 2030

U.K. body urges Japan to reconsider CO2 storage, ammonia fuel policy

Japan had IMF delete mention of coal in report on its economy