 Japan is committed to a post-Kyoto Protocol framework, but will not specify targets for emissions reductions beyond the pact's 2012 expiry as European nations have done, its chief climate negotiator said on Thursday. European Union ministers on Tuesday supported a binding commitment to cut the bloc's emissions unilaterally by at least 20 percent by 2020 compared to 1990 levels and also backed a call for industrialised nations to reduce emissions by 30 percent over that same period to help slow global climate change. Mutsuyoshi Nishimura, Japan's Special Envoy for Climate Change, said Japan will not let the Kyoto Protocol lapse without a framework to succeed it but shied away from any numerical commitments and said Europe had set a tough target. "Every advanced nation is in a vastly different situation," he told Reuters in an interview. "For example, Japan has really pushed for energy efficiency -- others haven't. "You can't just compare this by figures." Japan is the world's fifth largest greenhouse gas emitter and the biggest polluter that must cut emissions to meet its Kyoto obligations. "This does not lead to the conclusion that whilst Europe is 20 percent and Japan isn't, it doesn't mean that Japan isn't doing enough," he said. Nishimura stressed Japan is committed to meeting its Kyoto goal to cut its greenhouse emissions by 6 percent from 1990 levels by the 2008-2012 period but that it might need to take additional steps because its actual volume was 14 percent above the reduction target. "It will be very tough to meet the Kyoto Protocol target," Nishimura said. "But Japan will definitely achieve it." The government plans to buy about 100 million tonnes from the UN Clean Development Mechanism. This allows rich countries to invest in projects to reduce carbon emissions in poor nations and get emission credits in return. However, the government purchase plan only represents about 1.6 percentage points of Japan's six percent Kyoto reduction target, and experts have said the volume is too small and depends too much on business goodwill. "The government would apply additional steps without any delay," Nishimura said. Nishimura said it was essential that all nations work together and make the same efforts, or no new framework arrangement would last long enough to make a difference. "We are not going to let the current regime expire unless we have the new regime to replace it," he said of the 1997 pact agreed in Kyoto, a former Japanese imperial capital. "Kyoto is just the tiny first step. We need to have visions for several decades at least." The most serious shortcoming of the current protocol was the lack of top polluters such as the United States, China and India. "America's participation is the absolutely necessary condition," Nishimura said. "I believe the US will join sooner or later. If it joins, China and India will get moral pressure."