The G7 pledged on Sunday to quit fossil fuels faster and urged other countries to follow suit, but failed to agree to any new deadlines on ending polluting power sources like coal.

The language reflects the depth of disagreements among the allies on the balance between climate action and energy security, with host Japan leading a pushback against the most ambitious proposals discussed.

After two days of talks in the northern city of Sapporo, the bloc's climate and environment ministers vowed to "accelerate the phase-out of unabated fossil fuels so as to achieve net zero in energy systems by 2050 at the latest... and call on others to join us in taking the same action".

But they offered no new timelines beyond last year's G7 pledge to largely end fossil fuel use in their electricity sectors by 2035.

France's energy transition minister Agnes Pannier-Runacher said the "phase-out" wording was nonetheless a "strong step forward" ahead of the G20 and COP28 summits.

Britain and France had suggested a new goal of ending "unabated" coal power -- which does not take steps to offset emissions -- in G7 power grids this decade.

But with global energy supplies still squeezed by the war in Ukraine, the target faced opposition from other members, including Japan and the United States.

"I would obviously have liked to have been able to make a commitment to phase out coal by 2030," Pannier-Runacher told AFP.

But "it is one issue on which we can still make progress in forthcoming discussions, particularly at COP28", the UN climate conference in Dubai set for November.

Call to reduce 'gas demand'

The Group of Seven industrialised nations, which also includes Germany, Italy, Canada and the EU, pledged to end new plastic pollution by 2040.

Britain, Canada and the EU already belong to an international coalition with the same goal, but this is the first time Japan and the United States have made the 2040 commitment.

Plastic waste has doubled globally in two decades and only nine percent is successfully recycled, the OECD says.

The G7 ministers also urged a peak in global greenhouse emissions by 2025 at the latest -- language that experts say is aimed at the world's largest carbon emitter, China, which is targeting its own 2030 peak.

Other topics proved more divisive.

The ministers had been under pressure to announce bold steps after a major UN climate report warned last month that global warming of 1.5 degrees Celsius would be seen in about a decade without "rapid and far-reaching" action.

But campaigners feared backsliding on previous pledges such as ending new overseas fossil fuel financing.

G7 leaders said last year that the "exceptional circumstances" of Russia's war in Ukraine made gas investments "appropriate as a temporary response".

Sunday's statement contains similar language, but also sets multiple parameters around such investments and highlights the "primary need" for "gas demand reduction".

Still, climate campaigners warned the ambiguity sends the wrong message.

"The science is crystal clear that leaving the door open to investments in new gas or (liquefied natural gas) leaves the G7 off track for 1.5C," said Laurie van der Burg of Oil Change International.

Even so, Japan's minister of economy, trade and industry Yasutoshi Nishimura characterised the communique as "ambitious" and praised the G7 for "recognising diverse paths towards carbon neutrality".

'Somewhat positive'

Fatih Birol, executive director of the International Energy Agency, told AFP he was pleased with the statement.

It takes "our current energy security concerns" into consideration but also "provides a road map on how we deal with the climate crisis", he said.

The G7 stopped short of endorsing Japan's strategy of burning hydrogen and ammonia alongside fossil fuels to reduce emissions -- which activists say only serves to extend the lifespan of polluting plants.

Its statement simply notes that "some countries are exploring" the potential of hydrogen fuels, adding that this should be "aligned with a 1.5C pathway".

Attempts to commit to halving emissions from vehicles in the G7 by 2035 also floundered.

There is still time for Japan to "demonstrate its leadership in the decarbonised automobile industry" before May's G7 summit in Hiroshima, said Daniel Read of Greenpeace.

Overall, the nations had "made a somewhat positive step... in the right direction", but "failed to set out adequately ambitious action plans to drastically reduce emissions", he added.