Italian utility Enel SpA (ENEL.MI) has warned European ministers against changes to rules for carbon-emissions permits on the grounds that it could cut investment in projects aimed at reducing greenhouse-gas emissions, The Financial Times reports Thursday, citing the company.

Enel is the world's largest investor in the United Nation's Clean Development Mechanism, which allots carbon credits to reward emissions-reduction projects in emerging markets, the newspaper reports.

The credits can be used to meet emissions-reduction obligations under the European Emissions Trading Scheme. However, there is pressure to change the rules to make some types of projects--for instance, those that seek to reduce hydrofluorocarbons--ineligible for meeting EU commitments.

Enel says companies that have invested in these projects would face unreasonable losses on their assets if the EU were to impose retroactive "qualitative restrictions," the FT reports.

Enel has 13% of the 350 million metric tons of CO2-equivalent avoided emissions certified to date by the U.N. secretariat in
Bonn . Enel says about 60% of the 350 million tons came from projects to prevent the emission of industrial gasses, particularly hydrofluorocarbons and nitrous oxide, mainly in China .