The emissions trading scheme is the EU's key instrument to meet emissions reduction limits agreed under the Kyoto Protocol.

Estonia, Germany, Poland, Ireland, Lithuania, and Luxembourg have submitted their plans and some states have notified the Commission that their plans are late but on the way.

Commission spokesman Michael Mann said letters were being sent to 14 nations "giving them a month to tell us how the preparation of their NAP is going and when the Commission can expect to receive it."

"If we don't hear from them within that period, we will have to consider taking further action," he said.

The letters were called "pre-infringement" letters, he said. The Commission sends infringement letters to member states when it starts legal action against them for not complying with EU laws.

The "pre-infringement" letters were being sent to Austria, Belgium, Cyprus, the Czech Republic, Denmark, Finland, Hungary, Latvia, Malta, the Netherlands, Portugal, Slovenia, Slovakia, and Sweden.

Britain, France, and Spain were not getting letters because they had already indicated when their plans would be ready. Greece and Italy were also not getting letters at this time.

The EU emissions trading scheme sets limits on how much CO2 high-polluting industries can emit. Companies must buy CO2 allowances if they pollute above their limit, or they can sell extra permits if they come in below their targets.