The European Commission is reportedly considering a legal fight with the EU's top court over the handling of the EU Emissions Trading Scheme (ETS).

Earlier this week, the European Court of First Instance annulled commission decisions which sought to cut the CO2 emissions quotas of Poland and Estonia. The court defended the right of EU states to set their own CO2 quotas.

As reported by the BBC, a spokeswoman for the commission said: “We are very disappointed and are studying the judgment with a view to a possible appeal. Our actions will be guided by the need to protect the integrity of the carbon market and give legal certainty."

The spokeswoman for the commission also said that other EU member states such as Bulgaria, Hungary, Latvia, Lithuania and Romania were considering challenging the commission over CO2 emission allowances.

The commission had disputed the national allocation plans (NAPs) drawn up by Poland and Estonia for the 2008-2012 carbon trading period. The commission said Poland's CO2 quota should be cut by 27% and Estonia's by 48%.

The potential legal battle has been seen as a setback on the road to the Copenhagen Climate Change Summit in December this year.

Under the ETS, CO2 permits are traded, with heavy polluters buying extra permits from enterprises that pollute less. The scheme was launched in 2005 as a means to reduce carbon emissions across the EU.