Within the EU's executive commission, officials said there was now more momentum to tackle a deep-rooted problem that has attracted global attention.

Elzbieta Bienkowska, the commissioner responsible for industry, said: "Our message is clear: zero tolerance on fraud and rigorous compliance with EU rules. We need full disclosure and robust pollutant emissions tests in place."

The motor industry also backed more realistic testing.

The European Automobile Manufacturers' Association (ACEA), which represents companies including Volkswagen, BMW, Peugeot Citroen, Renault and Volvo, said it hoped the real-world testing conditions could be "finalised urgently".

But an EU source said there could still be difficulties in introducing new test procedures that match real-world driving conditions after years of official inertia and industry resistance to change.

"I still think the industry will say it's hard because they always do," one EU source said, speaking on condition of anonymity.

For its part, Germany faces resistance to any toughening of the test regime from its powerful motor industry. It markets its cars on a promise of clean performance, but tells the Commission its engines take years to design and new pollution standards should not be rushed.

JOBS AT STAKE

In 2013, Chancellor Angela Merkel won a delay in a law compelling car-makers to meet new CO2 emissions standards, saying jobs were at stake.

More recently, EU officials, speaking on condition of anonymity, said Germany had been lobbying for flexibility to soften a proposed new law to supplement laboratory testing with driving new cars on real roads.

In Europe, new models are authorised by type approvers before release and are not tested against EU standards after they are on the road.

The new law seeks to tackle the gap between levels of nitrogen oxides, particularly associated with diesel cars, recorded in tests and in the real world.

Members of the European Parliament this week seized on the Volkswagen crisis to demand swift implementation of the proposed real driving emission rules.

The discrepancy between real world emissions and those recorded in tests is not only due to the defeat devices Volkswagen has admitted using, which are illegal under EU law.

Practices such as the use of special fuel for the tests, turning off air conditioning, and using smooth driving surfaces, can all improve performance.

The Commission wants to know how many of the defeat devices Volkswagen used were rolled out in Europe. An EU ministerial meeting on Oct. 1 will address the issue.

But the Commission says its capacity is limited: it relies on national regulators to enforce its proposals, prompting non-governmental organisations in Brussels call for an independent EU-wide industry regulator.

The Commission has reports going back years that led to its decision in 2010 to supplement laboratory testing of cars with tests to reflect real-driving emissions. Five years later, it is still working on pushing through its new law.

(Additional reporting by Philip Blenkinsop; Editing by Giles Elgood)

By Barbara Lewis