Former communist countries' emissions have dived since 1990 because of an industrial collapse following their transition to liberalised markets, and while this is good news for climate change goals, it risks swamping the Kyoto trading tool.

The worry among green groups is that emissions cuts in eastern Europe are just because of the 1990 target baseline, and trading such margins would avoid real emissions cuts by other industrial countries.

Ukraine's Kyoto target is zero change on 1990 by 2008-12 and the 57 percent fall by 2004 would give it an annual 510 million tonnes carbon dioxide emissions reduction to sell.

This compares to an expected annual excess from 2008-12 of 200-300 million tonnes, according to the Japan Bank for International Cooperation (JBIC).

Ukraine is expected to have the second biggest such excess after Russia -- which has not yet published its 2004 data -- while Japan, Canada and the European Union are expected to be the furthest behind their Kyoto goals.

Ukraine's current surplus emissions reduction would exceed the expected annual demand for cuts of the EU, Japan and Canada combined between 2008-12 -- at 496 million tonnes CO2 -- according to JBIC data.

But western countries will be under pressure to make up their emissions cuts elsewhere -- either by pollution reduction at home, or through a Kyoto Protocol trading tool called the Clean Development Mechanism (CDM), where rich nations fund actual pollution cuts in poor ones.

The Ukraine report was posted on the UN website this week.