Tesla chief executive Elon Musk on Friday called for fossil fuel-powered cars "to be tested at random," as German giant Volkswagen's worldwide pollution cheating scandal continues to reverberate around the globe.

"The obvious move is to pick cars at random and then test the emission in transit," said Musk at the unveiling of the US-based electrical carmaker's new plant in the Netherlands, the first in Europe.

Musk's comments come in the wake of revelations that Volkswagen equipped 11 million of its diesel cars worldwide with software that can switch off those pollution controls -- except when it detects it is undergoing official testing.

"Clearly emissions-testing needs to be more rigorous," Musk said after the shock report, which has thrown the focus on electrical cars and its environmental advantages.

The scandal broke a week ago when US officials publicly accused Volkswagen of cheating and launched a probe which has also seen a growing list of other countries launch investigations.

"What we're seeing with diesel is that we've hit the limit," said Musk, whose new factory in Tilburg in the southern Netherlands will be able to pump out 450 high-end electrical cars a week.

He said he believed the German car giant "was under a lot of pressure to make improvements" in emission levels "and ran into a physical wall."

"After that, trickery is the only option," Musk said.