FILE PHOTO: A market ready particulate filter retrofit system for passenger cars to avoid diesel emission is pictured in a garage of German exhaust aftertreatment technology group Baumot in Witten, Germany, March 7, 2018. REUTERS/Thilo Schmuelgen

FRANKFURT (Reuters) - A working group of German government officials and car industry lobbyists has recommended hardware retrofits for older diesel vehicles as a way to avert inner-city bans, Frankfurter Allgemeine Sonntagszeitung reported.

A sub-committee of experts of Germany’s National Diesel Forum will back so-called selective catalytic reduction hardware refits to cut nitrogen oxides (NOx) emissions, the newspaper said in an excerpt of an article to be published on Sunday, made available to Reuters on Saturday.

There is, however, no consensus on who will foot the bill for the retrofits, which can cost 3,000 euros or more per car, the paper said.

It cited a government spokeswoman as reaffirming a plan for Chancellor Angela Merkel to decide on measures to cut NOx emissions this month.

A court ruled last week that Frankfurt, Germany’s financial center, must ban highly-polluting, older diesel vehicles from the city center from next February as part of a plan to improve air quality.

The city of Hamburg this year voluntarily blocked older diesel models from using selected trunk roads. Other cities including Aachen, Duesseldorf and Stuttgart, home to Daimler DAIGn.DE and Porsche VOWG_p.DE, are also considering bans.

The debate over air quality has been stoked by reports of persistently high NOx emissions in Germany’s largest cities and by Volkswagen’s admission in 2015 to have rigged diesel emissions tests in the U.S. with the help of engine control devices.