MUNICH -- Volkswagen Group added another twist to the controversy over diesel-emissions violations, apologizing for a test that exposed monkeys to engine fumes to study effects of the exhaust.
The study, conducted by a research and lobby group set up by VW, Daimler, BMW and Robert Bosch, was a mistake, VW said.
The New York Times reported on Friday about a 2014 trial in a U.S. laboratory in which 10 monkeys inhaled diesel emissions from a VW Beetle.
"We apologize for the misconduct and the lack of judgment of individuals," VW said in a statement. "We are convinced the scientific methods chosen then were wrong. It would have been better to do without such a study in the first place."
The revelations show the rocky road for Volkswagen as it emerges from its biggest crisis after the 2015 bombshell that the company installed emissions-skirting software in some 11 million diesel vehicles to dupe official tests. They also do little to help the poor public perception of the technology under scrutiny for high pollution levels in many European cities.
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.
Daimler said separately it would start an investigation into the study ordered by the European Scientific Study Group for the Environment, Health and Transport Sector.
"We believe the animal tests in this study were unnecessary and repulsive,” Daimler said in a statement. “We explicitly distance ourselves from the study."
BMW distanced itself from the trial, saying it had taken no part in its design and methods. It said it was "in no way influenced the design or methodology of studies carried out on behalf of the EUGT," adding that it does not carry out experiments involving animals and had no direct role in this study.
The study was financed equally by the three automakers and supplier Bosch. The study was ended June 30, 2017, and its findings had never been published, VW said.
Bosch said it left the group in 2013.
The EUGT commissioned the Lovelace Respiratory Research Institute in Albuquerque, New Mexico, which then designed an experiment where monkeys squatted in airtight chambers, inhaling fumes from a diesel Beetle, The New York Times reported.
To keep the animals calm during the four hours they breathed fumes, lab workers set up a television showing cartoons, the paper said.
The EUGT research was designed to counter a 2012 decision by the World Health Organization to classify diesel exhaust as a carcinogen, The New York Times said.
Reuters contributed to this report.