TOKYO -- Japan's prime minister announced on Thursday an ambitious new target for cutting greenhouse gas emissions, hours before he was to join a virtual climate summit hosted by U.S. President Joe Biden.

Prime Minister Yoshihide Suga said Japan will strive by 2030 to cut its emissions by 46% from 2013 levels, up from its earlier goal of 26%, to achieve carbon neutrality by 2050, a target he announced in October. He said Japan would further try to push the reduction as high as 50%.

"It will not be easy," Suga said. "In order to achieve the target, we will firmly implement concrete measures, while aiming to create a positive cycle linking the economy and environment and achieve strong growth."

Japan has been under pressure from environmental groups and European countries to do more than its earlier target of 26%.

Suga, during a visit to Washington last week, agreed to co-operate in leading global efforts to reduce carbon emissions by promoting clean energy technologies and implementing the 2015 Paris climate accord.

Progress toward reducing reliance on fossil fuels in Japan has been hindered by the prolonged closures of most of its nuclear plants after the Fukushima nuclear plant disaster in 2011.

Japan's current energy plan, set in 2018, calls for 22-24 per cent of its energy to come from renewables, 20-22 per cent from nuclear power and 56 per cent from fossil fuels such as oil, coal and gas.

Energy experts are discussing revisions to the plan for 2030 and 2050. The 2050 emissions-free target would require drastic changes and likely prompt calls for more nuclear plant restarts.

About 40 per cent of Japan's carbon emissions come from power companies, and they must use more renewable sources of energy while stepping up development of technologies using hydrogen, ammonia and other carbon-free resources, experts say.

Suga has said he will speed up research and development of key technologies such as next- generation solar batteries and carbon recycling.

He also promised to reduce Japan's reliance on coal-fired energy by promoting conservation and maximizing renewables, while promoting nuclear energy.