German automakers and politicians have come to an agreement to cut emissions by updating the software of 5 million diesel cars.

The VDA, Germany's auto industry association, said that German carmakers would install new engine software to make emissions filtering systems more efficient and tackle air pollution by cutting nitrogen oxide levels by 25-30 percent.

BMW, Daimler, Opel and Volkswagen will carry out retrofitting after approval from the KBA, Germany's federal motor authority, the VDA said.

Auto firms also agreed to make financial contribution to an initiative to clean up inner city pollution.

The agreement was reached at a summit in the country's capital, Berlin.

The "national diesel forum", a summit of politicians and car executives, was called yesterday by Germany's transport and environment ministers to address ways to reduce inner-city pollution.

Chancellor Angela Merkel was unable to attend the event due to being away on holiday.

Mike Ramsey, a car analyst at Gartner, welcomed the commitment to cut emissions.