German authorities have raided BMW’s Munich headquarters and its engine plant in Austria to search for evidence of the use of emissions-cheating software.

A month after the opening of an investigation into the suspected fraud, around 100 law enforcers have raided two of the manufacturer’s largest locations – 4,500 employees at the engine plant in Steyr, Austria, build 6,000 engines a day.

Prosecutors are looking into "erroneously allocated" software in about 11,400 vehicles of the BMW 750d and BMW M550d luxury models. It has confirmed intentions to recall these cars to "correct software”.

BMW became the latest manufacturer to attract the attention of regulators when it revealed that an internal investigation showed cars were producing higher emissions in real-world driving.

In an official statement released in February, BMW said engineers noticed “that correctly programmed software was wrongly used in a few models that were not compatible”. The brand then recalled 11,700 vehicles for software changes. However, Germany’s Federal Motor Transport Authority (KBA) said that it didn’t consider the software used in affected models to be a ‘defeat device’.

The latest raids suggest these findings have since then come up against opposing evidence – although it is not yet known what encouraged German authorities to go forward with the operation. BMW said that it doesn’t believe a defeat device has been used in its vehicles. The carmaker states that it “continues to assume that the situation was caused by an incorrect allocation of the software and does not represent a deliberate attempt to manipulate exhaust emissions”.

“The BMW Group takes the situation very seriously and has a significant interest in the circumstances being fully explained,” BMW said in a new statement. “The company is co-operating fully with the authorities. In addition, the company had already started an internal investigation and will obviously forward all information gathered, so far, to the authorities.”