The latest weakening of Japan's greenhouse gas emission reduction target was due to the loss of its dependence on nuclear power after the Fukushima disaster, Japanese chief negotiator Hiroshi Minami said Friday at the annual UN climate talks in Warsaw.

Earlier on Friday, the Japanese government announced in Tokyo its new target of cutting carbon emissions by 3.8 percent by 2020 compared to its 2005 levels. The figure means that Japan's emissions would be 3.1 percent higher compared to its 1990 levels, thus triggering strong disappointment particularly from the European Union and China.

"The new target is based on the assumption of no nuclear power station... Some say it's an easy target, but it is not," Minami said in a press conference, adding that the target might be revised once the country's economy gets better.

Japan had generated over a quarter of its power from nuclear energy before a quake-triggered tsunami crippled the Fukushima Daiichi nuclear power plant two years ago, since which its 50 reactors have stopped working for safety reasons.

The EU had already made a statement expressing its dismay, and most of the developing countries were disappointed as well, as Minami acknowledged in the press conference.

However, Minami said his country would remain committed to the long-term target of the 80-percent reduction by 2050 for developed countries and that Japan would focus on innovative and low-carbon technologies.