German authorities are due to report back to the European Commission (EC) by 19 August concerning the compliance of EU guidelines, as Mercedes-Benz waits for a French court decision surrounding its r134 refrigerant.

Mercedes and France are locked in an increasingly complex dispute that has seen the German automaker's A, B, CLA and SL models banned from being sold in the country, with Paris insisting it is merely applying the EC air-conditioning directive recommending use of r1234yf.

The German Kraftfahrt-Bundesamt (KBA) road safety authority is currently testing the EC-mandated refrigerant, which Mercedes claims is highly flammable in certain conditions, but Brussels has now involved its self-styled 'in-house science service' or Joint Research Centre (JRC) to assist.

"The JRC has been brought on board to assess assessments made by the KBA or other authorities," an EC spokesman told just-auto from Brussels. "The specific issue around the refrigerant has been clear and we have been clear.

"Up until now there has been no reason to assume the new refrigerant is not safe - if there is doubt cast on this there needs to be evidence provided."

The EC spokesman added European Union member states had welcomed the move with all 28 countries' road safety authorities meeting last month to discuss the impasse which has seen France block more than 5,000 Mercedes vehicles.

"It is an on-going process," said the EC spokesman. "The next step in terms of type approval is the German authorities [have] to come back to us by 19 August."

EC trade vice-president, Antonio Tajani, noted Brussels was informed last month France had decided to take temporary measures with regard to registration of vehicles which he said could be "in a situation of non-conformity" with the commission's mobile air conditioning directive.

"On the French safeguard, what happens is they notified us of the safeguard and it is now up to the commission to justify this," the EC spokesman said.

"There is no set timetable for that - we are looking to do [it] in a reasonable time frame."

Mercedes has requested a preliminary injunction to be imposed by France's highest judicial authority - the council of state in order to allow certification of its banned vehicles.

"Since the distortion of competition in the French market is rising more and more, Daimler has submitted a request for preliminary injunction at the French Conseil d'Etat," said a statement from the automaker.

"This is to achieve an earliest registration for the respective vehicles."

The KBA was not immediately available for comment.