The European Commission has charged German carmakers BMW, Daimler and VW with colluding to hold back the release of technology to clean tailpipe emissions.

The commission said on Friday that it had issued a statement of objections to the three carmakers.

"Companies can cooperate in many ways to improve the quality of their products," said Margrethe Vestager, the EU's antitrust czar. "However, EU competition rules do not allow them to collude on exactly the opposite – not to improve their products, not to compete on quality.

"As a result, European consumers may have been denied the opportunity to buy cars with the best available technology," she said.

The commission argues that the companies had cooperated to block the release of emissions-cleaning technologies between 2006 and 2014. The collusion covered catalytic converter systems, which reduce nitrogen oxide emissions through the addition of the additive AdBlue to the exhaust stream, and particle filters.

The companies now have a chance to respond to the commission's charges.

If, after hearing the companies' defence, the commission decides there is sufficient evidence of a breach of EU competition rules, they can be fined up to 10 percent global turnover.

The commission has fined several companies in the automotive sector for breaching competition rules. They include suppliers of car seats, alternators and starters, air conditioning and engine cooling systems, lighting systems, occupant safety systems, braking systems and spark plugs.