Volkswagen AG has been accused of violating the U.S Clean Air Act by installing illegal devices to impair emission control systems in their numerous vehicle units.

On Monday, the U.S. Justice Department filed a civil lawsuit against the multinational automotive manufacturing firm, alleging that the company illegally installed a device to their 600, 000 units. It is believe that those devices can impair emission control systems but at the same time can damage human health too.

If ever proven that the allegations are true, Volkswagen, along with its Porsche and Audi models could possibly be facing an enormous penalty. Theoretically speaking, the automotive company could face fines more than $90 billion or as much as $37,500 per unit for the violation of the law, as per The Globe And Mail.

The lawsuit was first filed in the Eastern District of Michigan, then it was transferred to Northern California on behalf of the Environmental Protection Agency that accuses the company of four counts of violation of the Clean Air Act.

The senior Justice Department official said that they are "alleging that they knew what they were doing, they intentionally violated the law and that the consequences were significant to health."

It was in Sept when Volkswagen first admitted that they installed cheat devices on their several 2.0 liter diesel units, but the lawsuit insisted that the firm failed to reveal about the their other models that were installed with the particular device.

The government said that the particular device used by the Volkswagen can detect if the unit are on a flatbed or if it's on the road. But once on the road the installed software automatically shuts down the emissions control system, allowing the units to release dangerous levels of air pollution that subsequently damages the human health and environment.

As for the Volkswagen, the company ensured that they will continue to cooperate with the government agencies to solve the matters.