The Japanese government has admitted it may have to abandon a target to cut carbon emissions by 25 per cent by 2020 in the wake of the Fukushima crisis.

The government signed up to the pledge in 2009, but the collapse in public confidence in nuclear power since the disaster in March 2011 forced the government to mothball plans for nine new reactors and begin stress testing the current 54, the last of which was shut down on May 5.

Green campaigners fear the energy gap may be filled by ramping up generation from fossil fuels and figures published earlier this week by the US Energy Information Administration seem to suggest this is the case.

They show from January to April this year, electricity generated from natural gas, oil and coal-fired plants was up 40 per cent on the same time in 2011, making up 90 per cent of Japan’s total electricity, compared to an average of 64 per cent last year.

At the same time, deputy Prime Minister Katsuya Okada told a meeting earlier this week that the administration was considering a new target given the change in circumstances, the Japan Times reported today.

He said the current 25 per cent goal “is a number computed on the premise that we will depend on nuclear power to a fair degree” adding that “I have no doubt that an overall review will be necessary”.

Okada said the government had not yet worked out what this target may be, but would “decide on a [percentage] at some point and convey it” to the international community.

Japan ruled out signing up to a new round of international emissions cuts under an extended Kyoto Protocol at last year’s climate summit in Durban, but is introducing a swathe of subsidies for clean energy technologies next month with the aim of increasing production 13 per cent by 2013.