"The minister has no understanding for such tests, which damage animals and humans and that do not serve science but merely PR aims", Mr Strater said.
These tests were said to have taken place between 2012 and 2015.
According to the Stuttgarter Zeitung, the experiments were carried out at an institute of the University Clinic Aachen and involved the group having to breath in varying different concentrations of nitric oxide after which they were physically examined for any side-effects.
German carmakers condemned experiments that exposed humans to diesel fumes, promising to investigate the tests whose disclosure threatens to open a new phase in an emissions controversy that's dogged the industry since 2015.
"We apologise for the misconduct and the lack of judgment of individuals", A spokesperson for Volkswagen said in a statement.
"That a whole industry has apparently attempted to dispense with scientific facts through brazen and dubious methods only makes the whole thing even more outrageous", Hendricks said. Scientists had in no way been influenced in their work by the likes of Volkswagen, BMW and Daimler, he said.
Daimler, which owns Mercedes, told the AFP news agency it "condemns the experiments in the strongest terms".
Hoping to defend diesel's environmentally-friendly reputation - and the valuable tax breaks that go with it - the EUGT commissioned the tests from the US-based Lovelace Respiratory Research Institute.
According to a New York Times report, a company referred to by its German initials EUGT was formed by the car-maker trio in 2007 and commissioned tests on live mammals to prove the cleanliness of diesel engines. The Beetle was one of those 11 million vehicles installed with software which meant the cars wouldn't exceed test limits for emissions.
The 10 monkeys were placed in sealed chambers in front of TVs showing them cartoons, as Volkswagen Beetles drove on a treadmill, and their diesel fumes were pumped into the breathing spaces.
Record auto sales in 2017 provided evidence that VW's popularity with consumers has not been hurt by "dieselgate", but analysts said the revelations about the diesel exhaust tests could seriously undermine the carmaker's transparency drive, a pillar of its post-dieselgate transformation.
Neither the monkey test nor the Aachen test revealed anything of use to the companies involved, with the monkey test being so pointless no report or conclusion was ever released. VW admitted in a statement on Monday that some employees in its legal department, technical team, and at VW of America were aware of the tests, yet it denied the tests had been discussed at a Board level.
Volkswagen apologised for the animal testing at the weekend, saying the group "distances itself clearly from all forms of animal abuse".
What do we know about the tests?
BMW, while distancing itself from the studies, said the assessment of the trial at Aachen University before an independent body with appropriate expertise - such as the ethics commission - should be taken into account.
VW's supervisory board representative and chief controller, Hans Dieter Pötsch, said on Monday he was struggling to understand how the tests had been allowed to be carried out, calling them "in no way understandable".
However, and here's the rub, the testing on animals will continue beyond cosmetics, with the monkey study a case in point of how companies and research organisations side-step laws.