An Audi and two Skoda passenger diesel vehicles imported into Singapore were found to be fitted with devices to cheat emission tests, following investigations by the National Environment Agency (NEA) and the Land Transport Authority.

These devices are similar to those found earlier in 662 Volkswagen (VW) diesel vehicles here, in a worldwide scandal involving German carmaker Volkswagen. Audi and Skoda are brands under the VW group.

The latest three vehicles were imported directly and not sold or registered by local car distributors.

In a statement yesterday, the NEA said it will continue to work with agencies here and overseas as well as automobile manufacturers to ensure that new and in-use vehicles comply with the emission standards under the Environmental Protection and Management (Vehicular Emissions) Regulations.

In September, regulators in the United States had found that the German manufacturer had incorporated a device in its diesel cars to cheat during emission tests.

The US Environmental Protection Agency's broadening search has also revealed that more Volkswagen, Audi and Porsche vehicles have been equipped with such defeat devices.

Media reports said that these devices - installed in 11 million vehicles worldwide - adjusted diesel engine performance during testing conditions, and allowed up to 40 times the limit of smog-creating nitrogen oxide pollution during normal driving.

NEA said it is investigating whether and how many of such vehicles here have been affected.

VW Singapore met customers last month to apologise, and assured them that their cars were roadworthy, adding that solutions to fix their cars were on the way.

This may require hardware modifications, such as adding a nitrogen oxide treatment system to the car's exhaust.