BRUSSELS (AP) - The European Union yesterday sued Greece, Belgium, Finland and Italy for failing to take steps to introduce a system enabling companies to trade greenhouse gas emissions under the Kyoto agreement on global warming.

The EU head office said the four members had missed a December 31, 2003 deadline to adopt plans for an EU-wide initiative to start trading in “carbon credits.” They now face legal action in the European Court of Justice.

A European Commission statement said the reasons for the delay were bureaucratic, not because the four nations oppose the United Nations’ 1997 Kyoto Protocol on cutting greenhouse gas emissions.

Under the Kyoto accord, the EU must cut its output of carbon dioxide by 8 percent from 1990 levels by 2012. So far, emissions are down only 2.9 percent.

The trading system enables companies that emit fewer gases than allowed to sell unused “carbon credits” to others that overshoot their targets.