The European commission has started legal action against the UK and six other EU states for failing to act against car emissions cheating in the wake of the “dieselgate” scandal.

VW was forced to recall nearly half a million cars from the US market last year after it was revealed that the company had used sophisticated “defeat devices” to game emissions tests. Other manufacturers have also used techniques to give lower emissions readings in lab tests than in real world driving.

Germany and Spain are among the nations accused of failing to set up penalty systems to deter such violations of emissions law and failing to punish offenders where crimes have been committed. The accused countries have two months to respond, after which the commission could send a “reasoned opinion” before ultimately filing a suit at the European court of justice in Luxembourg.

The EU’s industry commissioner, Elżbieta Bieńkowska, said: “Abiding by the law is first and foremost the duty of car manufacturers. But national authorities across the EU must ensure that car manufacturers actually comply with the law.”

The UK is one of four countries accused of issuing approvals for VW Group cars and not applying national provisions or penalties, despite the company’s use of illegal software. The commission argues that the UK and Germany have unlawfully refused to disclose details of national investigations into potential irregularities in nitrogen oxide (NOx) emissions by VW and other carmakers.

“The commission has bared its teeth and told member states it’s time to act against the dishonest carmakers that have been manipulating tests and poisoning the air by turning off exhaust treatment systems,” said Greg Archer, the clean vehicles director of the green campaign group, Transport and Environment. “Dirty diesels must now be recalled and fixed and national regulators must stop protecting their friends and clients in the automotive industry.”

Under the current approval system, national authorities are responsible for checking that car models meet EU regulations before they can be sold, and for sanctioning auto manufacturers that break the law.

Brussels has tabled proposals for greater EU oversight of national approval systems, although measures to mandate independent inspections of vehicles were deleted from a draft version of the regulation, after interventions from EU states’ transport ministries. This is reported to have angered Bieńkowska.

French MEP Karima Delli, who is vice-president of the European parliament’s inquiry into dieselgate, said that while France had been spared legal papers thus far, “it is probably only a question of time”.

She said: “The final results of the French inquiry launched by environment minister Ségolène Royal have yet to be published, and judicial proceedings against several car manufacturers including Renault are still ongoing. It remains to be seen if the commission will use this evidence to launch infringement procedures against France in the near future.”

A European shift towards less polluting vehicles could save consumers between €4,400 and €9,400 (£3,700 and £8,000) in lifetime fuel costs by 2025, according to a recent report (pdf) by the European consumer group BEUC.