Germany’s motor vehicle regulator on Wednesday widened its emissions probe to 23 local and foreign brands in the wake of Volkswagen’s emissions scandal. The move came after it found signs of elevated pollutants in diesel cars in the initial results following tests. 

The Kraftfahrt-Bundesamt (KBA) regulator reportedly said it found "partly elevated levels of nitrogen oxides" in some of more than 50 models, which included vehicles from BMW, Mercedes and General Motors Co.’s Opel, triggering further tests on suspicion of manipulation of emissions from diesel engines. Germany's Transport Minister Alexander Dobrindt announced over the weekend that diesel vehicles would be subjected to strict checks.

"Since the end of September KBA has been investigating whether further manipulation of emissions, of nitrogen oxides in particular, is taking place in the market," KBA said, in a statement, according to Reuters. KBA also reportedly cited "verified indications from third parties regarding unusual pollutants emissions.”

KBA plans to evaluate the data further after discussions with carmakers, following which the agency can work on any legal action, Bloomberg reported. 

The tests on other brands began after Volkswagen admitted it had rigged emission levels by employing a type of software, a so-called defeat device, that indicated the vehicles' emissions as far lower than they actually were.

The Volkswagen scandal came to light in September after scientists at a University of West Virginia laboratory tested several of the company's diesel vehicles and found their carbon emissions were as much as 40 times the legal limit in the U.S. The "defeat device" affected at least 11 million Volkswagen diesel vehicles worldwide, including about 500,000 in the U.S.

Earlier this week, the European Union's climate and energy commissioner, Miguel Arias Canete, asked Volkswagen to provide “further clarifications” on the emissions scandal, the Wall Street Journal reported.

Last week, the U.S. Environmental Protection Agency (EPA) claimed that Volkswagen installed software designed to defeat emissions tests on 2014 to 2016 vehicles with 3.0-liter, six-cylinder diesel engines, which included Audi and Porsche models. The same week, Volkswagen executives also admitted that about 800,000 vehicles, mostly in Europe, consume fuel and emit harmful gases at higher levels than previously known.