Japan will announce as early as next week that it intends to buy carbon credits from Hungary, a move that could foreshadow a much larger purchase from Russia - and one that would provoke criticism as a means of meeting its obligations under the Kyoto protocol.

Japan could become the world's biggest buyer of -carbon credits because, under Kyoto, it has pledged to cut emissions to 6 per cent below 1990 levels but is currently 8 per cent above.