Japan, Taiwan and the U.S. have accused the EU of failing to cut tariffs on electronic hardware imports.
The World Trade Organization gave the EU a June 30 deadline to cut import duties on flat-panel displays, television set-top boxes and multifunction printer-copies after a complaint from the three countries in 2008.
They argued that the EU had broken the global Information Technology Agreement with the import duties of the three products, which U.S. trade officials estimated amounted to $7 billion in 2009.
The EU said that it had done so, but the three complainants disagreed, a source close to the WTO said.
Representatives from the three countries met the WTO this week and said the revised EU import rules were ambiguous and might not be applied in the same way across the 27-nation bloc, the source said.
The three highlighted a 2.2 per cent import duty for some multifunctional digital copiers and questioned the EU's report that it had repealed duties on flat panel displays in 2009, the source said.
Under WTO complaint procedures, after a 15-day consultation period, the three countries would be able to ask a WTO panel to let them take countermeasures to punish the EU for failing to comply.