More than 20 countries, including Japan and the United States, vowed on Saturday to triple the world's nuclear energy capacity by 2050 to reduce global carbon emissions, according to their statement.

The declaration, released by the U.S. Department of Energy, points to the "key role of nuclear energy in achieving global net-zero greenhouse gas emissions" and comes as the 28th session of the Conference of the Parties to the U.N. Framework Convention on Climate Change, or COP28, is under way in the United Arab Emirates.

Global leaders attend an event related to COP28 for tripling nuclear energy capacity in the United Arab Emirates on Dec. 2, 2023. (AP/Kyodo)

The countries that endorsed the declaration also include Britain, Canada, France, South Korea, Ukraine and the UAE. In the declaration, they said they will cooperate to triple nuclear capacity by 2050 from 2020 levels.

However, the statement was met with criticism by climate activists.

In a press release by, an international environmental organization, Japanese campaigner Masayoshi Iyoda said that Japan needed to "stop using the climate crisis to justify its addiction to nuclear energy while it allows carbon-intensive industries to prolong fossil projects."

The Japanese government passed a bill earlier this year to allow nuclear reactors in the country to be operated beyond the current limit of 60 years and expects about 20 to 22 percent of its energy to come from nuclear energy by fiscal 2030.

The bill aims to ensure adequate energy supply for the country, where the use of nuclear power has raised concern among the public in the wake of the 2011 nuclear crisis at the Fukushima Daiichi plant in northeastern Japan.

The crisis led to the closure of all nuclear reactors, with most remaining offline as they must meet stricter safety standards introduced after the disaster before they can restart.

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