Prosecutors in Germany have raided high-end carmaker BMW in a fraud probe relating to more than 11,000 vehicles they suspect were rigged to appear less polluting in regulators' tests.
"On suspicion of fraud in around 11,400 cases, prosecutors have opened an investigation against unidentified workers or managers at BMW and raided BMW headquarters in Munich and another site in Austria," the authorities said in a statement.
"There is an initial suspicion that BMW uses or has used a 'defeat device' that activates during testing" by regulators to determine emissions levels, prosecutors added.
A defeat device refers to a system like those built into more than 11 million cars worldwide by Volkswagen in the "dieselgate" scandal.
In the VW case, it operated exhaust treatment systems to remove harmful nitrogen oxides (NOx) at full effectiveness when cars detected they were undergoing stationary tests, while shutting them off in on-road driving.
As for BMW, "evidence gathered in Munich and Austria must now be looked over, the investigation is only just getting started," the prosecutors said.
In a statement on Tuesday, BMW confirmed the raids and repeated the company's stance that "a correctly programmed software subroutine was mistakenly allocated to incompatible models".
The software was not used for "deliberate manipulation of the exhaust treatment system," it insisted.
BMW in February admitted the software was present in some vehicles and said it would recall them for a software update as soon as one was approved by the KBA German vehicle licensing authority.
The programme was not built into the first cars of the two types affected -- the 750d and M550d -- to roll off assembly lines, rather only a smaller number beginning "well after the start of production" the group said.
BMW "is supporting the authorities fully in their work" and has also launched an internal investigation, the firm added.