German high-end carmaker BMW on Friday recalled thousands of diesel cars for a software update, after reports it had admitted to authorities they released more harmful emissions on the road than in the lab.

BMW "noticed during internal testing that correctly programmed software was wrongly used in a few models that were not compatible," the group said in a statement.

The Munich-based company "immediately informed the relevant authorities... (and) therefore plans to recall 11,700 vehicles worldwide," it added.

"Niche motor variants of an already discontinued generation of the 5-series and 7-series built between 2012 and 2017" were affected, BMW said.

Der Spiegel magazine reported earlier Friday that BMW had admitted to the KBA vehicle licensing authority that some of its cars included software that could mislead regulatory tests for levels of harmful nitrogen oxides (NOx).

Suspicion fell on the entire German car industry after Volkswagen -- parent company of BMW competitor Audi -- admitted in September 2011 that it deliberately built such "defeat device" software into 11 million cars worldwide.

But BMW has so far been able to trumpet clean diesel credentials.

After the KBA recently found no issues with a 3-series car that environmental activists had suggested might include a defeat device, development chief Klaus Froehlich stated baldly that "vehicles from the BMW group were not manipulated. Our diesel engines are clean."

On Friday, a spokesman for the company told Spiegel that "we do not consider the software to be a 'defeat device'."

The offending software had been "mistakenly" loaded into cars with a different system for removing harmful nitrogen oxides (NOx) from the exhaust than originally intended, the group said in its later statement.

"Corrected software will be made available for these vehicles after approval by the relevant authorities," BMW said.