The small Baltic state of Latvia has become the latest member state to start legal action against pollution caps imposed by the European Commission.
Environment minister Raimonds Vejonis said he was unhappy with the way the commission had calculated its carbon dioxide (CO2) emissions quota for the country, according to AFP news agency.
Brussels had asked Riga to cut its CO2 emissions to 3.43 million tonnes a year for the next phase of the carbon emissions trading scheme, beginning in 2008 and running for four years.
The scheme is the commission's key policy for getting the 27-member EU bloc to adhere to the Kyoto Protocol on emissions cutting and allows industry to buy and sell pollution credits.
During the first phase, beginning in 2005, the system was undermined when Brussels allowed member states to allocate too many credits, prompting the commission to tighten the system from next year.
Estonia had asked to be allowed to pollute to the tune of 6.25 million tonnes a year between 2008 and 2012.
Latvia's decision to challenge Brussels in the courts follows similar moves made by Poland, the Czech Republic, Slovakia, Hungary and Estonia.
All six countries joined the EU in 2004 and are playing economic catch-up with richer western European member states.
They fear that pollution-cutting moves, imposed by Brussels, will curb their competitiveness and hamper their attempts to get themselves on an economic par with richer EU countries.
The competitiveness versus being green faultline was exposed earlier this year in the run-up to a major EU environment summit in March -- with several of the 2004 member states arguing that it was unfair to expect them to make the same green sacrifices as well off countries such as Germany and France.
In the end, EU leaders managed to agree a series of ambitious green goals at the summit, including cutting carbon emissions by 20 percent by the end of the next decade.
However, the difficult question of burden-sharing in the fight against climate change was left untouched.
The commission is set to come with proposals on how to reach these goals - and what each member state needs to do - later this year.
The proposals are set to see a re-emergence of the same economy versus environment arguments across the EU.