Tests that involved humans and monkeys inhaling diesel fumes have been denounced by the German government.

News of the research, which was funded by German car manufacturers, has shocked the German public and has drawn condemnation from the nation's politicians.

According to German media, a body called EUGT carried out the health impact research, with direct funding from BMW, Daimler and Volkswagen.

VW's reputation is still feeling the effects of the diesel exhaust scandal of 2015. Software was installed in VW models which helped cars defeat emissions tests.

The German government has condemned the latest tests and has demanded more information.

EUGT stands for European Research Group on Environment and Health in the Transport Sector.

It was dissolved last year.

Chancellor Angela Merkel's spokesman, Steffen Seibert, said, "These tests on monkeys or even humans cannot be justified ethically in any way."

The tests were described as "abominable" by Environment Minister Barbara Hendricks, who also said she was shocked the scientists involved agreed to carry them out.

According to a report in the New York Times, the EUGT was set up to oppose a 2012 move by the WHO to categorise diesel fuel as a carcinogen.

It reported that 10 monkeys were exposed to fumes in 2014. The tests were carried out in Albuquerque, New Mexico, and in involved a VW Beetle, among other cars.

In another EUGT experiment, 19 men and six women inhaled diesel fumes - according to reports by Stuttgarter Zeitung and SWR radio.