TOKYO (AFP) - Japan said on Friday it was dramatically scaling back its greenhouse gas emissions target after the Fukushima nuclear accident forced the country to turn to fossil-fuel burning energy sources.

Chief Cabinet Secretary Yoshihide Suga said the new target for 2020 - 3.8 percent below 2005 levels - replaces an ambitious goal to slash emissions by one-quarter from 1990 levels, which had been hailed by environmentalists.

Japanese media said the new target - which accounts for Japan idling its nuclear reactors after the worst atomic accident in a generation - represents a 3.0 percent rise over 1990 levels.

Suga, the government's top spokesman, said the earlier target set in 2009 by a centre-left government under then-prime minister Yukio Hatoyama was "totally unfounded".

"Our government has been saying... that the 25 percent reduction target was totally unfounded and wasn't feasible," he told reporters in Tokyo.

A foreign ministry official said the new target would likely be announced next week at a 12-day climate talks summit in Warsaw which kicked off on Monday.