Seoul prosecutors said Thursday Volkswagen, faced with an emissions cheating scandal, appears to have sold thousands of vehicles with unauthorized exhaust pipes.

Seoul Central District Prosecutors' Office said Audi Volkswagen Korea arbitrarily changed key parts that affect emissions on about 50,000 cars, including Audi A7s, without getting authorized by the Ministry of Environment.

Under the local law, failure to be authorized for changes could lead to a fine of up to 10 billion won (US$8.62 million) per model.

Prosecutors are also trying to determine the connection between the use of unauthorized parts and Volkswagen's emissions scandal.

"We believe Volkswagen may have used improper parts to quickly release its vehicles to meet the demand," an official with the prosecutors' office said. "We've left many different possibilities open in our investigation."

Prosecutors recently confiscated 956 vehicles of Audi Volkswagen Korea in its inspection center in Pyeongtaek, Gyeonggi Province, and they said 606 of them had been imported without proper environmental authorization.

The German carmaker took a beating after its "diesel gate" surfaced last year, when it was found to have faked emissions results for some of its diesel models to meet the tight regulations in the United States.

The environment ministry here on Tuesday rejected Volkswagen's plan to recall its vehicles that fabricated emissions results, saying the local unit of the German carmaker did not admit to using a defeat device to trick vehicle testing.

The carmaker's initial recall measures submitted in January were also rejected by the ministry for insufficient data and lack of a proper outline to rectify the shortcomings of the vehicles affected. (Yonhap)