Three German automakers appear to have commissioned or supported studies that exposed monkeys and humans to exhaust fumes and nitrogen dioxide, according to German media reports on Monday.
Behind the tests was the European Research Group on Environment and Health in the Transport Sector (EUGT) - a since defunct organisation funded by German vehicle giants Daimler, BMW and Volkswagen Group. The revelation came days after the New York Times reported that the research group had carried out similar tests on monkeys in the U.S.in 2014.
Germany's Stuttgarter Zeitung newspaper reported on Sunday that EUGT had also sponsored scientific studies testing nitrogen dioxide, a gas found in exhaust fumes, on 25 "healthy" young people.
"We expressly distance ourselves from the studies and the EUGT".
In a statement over the weekend, Volkswagen apologised for the misconduct and lack of judgment shown by individuals.
Dieselgate has just received a new lease of life as news emerges of emissions testing conducted on humans and monkeys between 2012 and 2015.
The goal was to prove that various technologies to improve diesel emissions were working.
The first publications in this regard focused on monkey experiments that the EUGT commissioned back in 2013 to the Lovelace Biomedical laboratory in Albuquerque NM (USA).
The tests haven't had any negative consequences for the health of either the animals or the humans, but the news has caused public outcry, with many people arguing that those responsible for the initiative must be punished.
Nitrogen dioxide was the gas at the center of a scandal in which Volkswagen acknowledged it had cheated on diesel emissions tests, which previous year led to the U.S. Department of Justice charging the company with conspiring to defraud the government and violate environmental regulations.
In a statement on its website, Daimler said it was "appalled" by reports of the extent of the study, and is "expressly distancing" itself from the EUGT, adding that it "condemns the experiment in the strongest terms".
In an additional twist, the Beetle model used in the test was among the vehicles that were rigged to conform to test limits, The New York Times reported.
Strater said the minister wants an "immediate and detailed" explanation about why the tests were conducted and said a commissions set up to look into the VW emissions scandal will now probe the EUGT project.
"The BMW Group in no way influenced the design or methodology of studies carried out on behalf of the EUGT", BMW says in a statement (via Deutsche Welle).
VW is no stranger to controversy following the 2015 dieselgate scandal where the carmaker admitted fitting software created to cheat emissions testing to 11 million vehicles.
In the study, LRRI placed 10 macaque monkeys in an airtight chamber while tailpipe exhaust was pumped into the room, according to the Times report.
"These tests on monkeys or even humans can not be justified ethically in any way", said Chancellor Angela Merkel's spokesman, Steffen Seibert. And in 2016, VW agreed to pay up to $14.7 billion to resolve claims from consumers and the USA government.
The German state of Lower Saxony, a major owner of Volkswagen, has demanded a full report of the 2014 tests.