Prosecutors summoned an executive of the local unit of Volkswagen on Monday over their widening probe into the German carmaker's alleged irregularities that came into light following its emissions scandal.

The Seoul Central District Prosecutors' Office summoned the executive in charge of the certification process, identified only by his surname Yoon, for questioning to gain a reference.

Prosecutors said his status can change to that of a suspect following the investigation, if necessary.

Yoon is the first among several related company officials on the summons list.

The legal action came a few days after prosecutors said last week that Volkswagen Audi Korea allegedly submitted 37 doctored reports of the vehicles' emissions results and noise levels from 2010 to 2015.

Under local law, all imported cars should first receive approval from the National Institute of Environmental Research of their emissions results and noise levels.

The automaker allegedly submitted existing test results of similar models when the ones on the new models were not prepared in a bid to cut prices and fast-track the launch of new models into the local market, according to prosecutors.

Later on Monday, prosecutors said they found 54 additional reports on 20 more models -- including the Audi A4, A8 and Golf -- that are suspected to have been fabricated.

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

Officials said they plan to question Yoon on the allegations raised and whether the German headquarters was involved in the process.

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

The ministry rejected two previous recall plans in January and March for insufficient data and the lack of a proper outline to rectify the shortcomings of the vehicles affected. (Yonhap)