 The EU hopes to agree targets in time for a new international deal |
But several central and eastern European countries objected to the measures during a meeting in Brussels.
Poland which relies on coal-fired power stations has called for changes while other countries dispute the use of 2005 figures to work out their targets.
Despite their differences, EU member states hope to push through the climate change proposals by December.
French Environment Minister Jean-Louis Borloo said it was "extremely important that there be a political deal" before talks began on finding a successor to the Kyoto Protocol in Poland.
'Negative impact'
That view was echoed by UK Environment Minister Hilary Benn but Polish minister Maciej Nowicki said there should be a bigger role for investing in cleaner ways of extracting energy from fossil fuel.
He said the proposals "would have a negative impact on the living standards of Poles" as well as on Polish business.
Although the 20% cut in emissions, for many western countries, is based on 1990 levels, for newer EU member states the target is based on 2005 levels.
Hungary, Slovakia, Romania, Lithuania and Bulgaria all voiced opposition to their target but EU Environment Commissioner Stavros Dimas said there was insufficient information about their emissions levels in 1990.
Their carbon emissions would have been far greater in 1990 because of a heavy industrial reliance on coal.
