Officials and lawmakers negotiating an overhaul of the EU carbon market are struggling to reach a compromise over plans to levy CO2 costs on suppliers of polluting fuels, potentially putting the bloc's climate change targets at risk. 

Launched in 2005, the emissions trading system (ETS) is the European Union's main tool for cutting greenhouse gases, which it does by forcing power plants and factories to buy CO2 permits when they pollute and capping the supply of permits.

The scheme has slashed emissions in those sectors by 43% since its launch but is facing a revamp as the EU strives to hit a target of a 55% cut in net emissions from 1990 levels by 2030.

The revamp, proposed by the European Commission last year, is seen as critical because transport emissions are rising, and most buildings in Europe are heated by fossil fuels, churning out roughly a third of total EU emissions.