Japan's new Prime Minister Yoshihide Suga has set a deadline of 2050 for the world's third-largest economy to become carbon neutral, significantly firming up the country's climate change commitments.

Delivering his first policy address since taking office, Mr Suga placed the environment front and centre as Japan plays catch-up with climate pledges made by other major economies.

"We will bring the total amount of greenhouse gas (emitted by Japan) to net zero by 2050, meaning carbon neutral," Mr Suga told parliament.

"I declare we will aim to realise a decarbonised society," he added, to applause from Diet members.

Japan had previously only aimed to achieve carbon neutrality some time in the latter half of the century, a goal that critics called vague.

However the new target was praised by activists and experts, and puts Japan on the same timeline as Europe and Britain and a decade ahead of China, which last month set a 2060 goal.

China's Communist leadership are due to discuss Xi Jinping's ambitious carbon neutral pledge in talks that began today on the country's economic strategy for the next five years.

The climate goals, which challenge the world's biggest polluter to reach peak emissions in 2030 and go carbon neutral 30 years later, are the most concrete environmental action announced by China yet, but are thin on public detail.

In Japan, Mr Suga did not give precise details on how the country, which is still heavily reliant on coal, will meet the deadline but said technology would be essential.

"The key is innovation," he said, citing examples including next-generation solar batteries.

He added that Japan would also push the use of renewable energy and nuclear power, stressing that safety would be a priority - a key point in a country that suffered the Fukushima nuclear disaster nearly a decade ago.

Japan, which is a signatory to the Paris climate change agreement, was the sixth-biggest contributor to global greenhouse emissions in 2017, according to the International Energy Agency.

It has struggled to cut carbon emissions after shutting down nuclear reactors following the 2011 meltdown in Fukushima sparked by a devastating earthquake and tsunami.

Reliance on fossil fuels like coal increased after the Fukushima disaster as public anger over the accident pushed all of the country's nuclear reactors offline temporarily.

Japan's 140 coal-fired power plants provide nearly a third of its total electricity generation, and coal is the second-biggest power-generation method behind LNG-fired plants, which provide 38% of the nation's needs.