The European Commission has launched legal action against seven nations including Germany and the UK for failing to clamp down on the emissions cheating exposed by the the "dieselgate scandal".

The move reflects mounting frustration in Brussels over how national authorities have responded to the widening scandal, which began with revelations last year that German carmaker Volkswagen had used illegal software, known as defeat devices, to mask emission of dangerous nitrogen oxides (NOx) that cause respiratory diseases and lung cancer on tests.

Officials in Brussels said Germany, Britain, Spain and Luxembourg were accused of not imposing the same kind of penalties VW faced in the United States over its use of illegal software.

The European Commission has further called on Germany and the UK, claiming both refused to share details on breaches of EU emmissions laws uncovered in national investigations this year.

The other nations' actions under the spotlight are the Czech Republic, Lithuania and Greece.

Thursday's notice is the first step in what is known as infringement procedures, allowing the EU to ensure the bloc's 28 nations abide by agreed EU-wide regulations. Member states have two months to respond.

Since the VW revelations, it has emerged that other manufacturers, which include Gaimler's Mercedes-Benz and General Motor's Opel and Fiat, have also used sophisticated, software-based techniques so their cars pass official tests despite emitting far higher levels of NOx on the road. The practices include switching off emissions control systems outside of narrow temperature ranges, or after a period of time just longer than the tests.