SINGAPORE -The Volkswagen diesel models affected by a widening emissions-cheating scandal are not sold in Singapore, the National Environment Agency (NEA) said.

Based on the information available so far, the NEA "understands that the cases reported in the United States pertain to Volkswagen diesel models that are not sold in Singapore", it said in a statement late Tuesday.

However, the agency will investigate and take "appropriate action against any cases of fraudulent emissions claims".

Shares in Europe's biggest carmaker plunged almost 20 per cent on Monday after it admitted using software that deceived US regulators measuring toxic emissions in some of its diesel cars.

The affected diesel cars have so-called Type EA 189 engines which are built into about 11 million Volkswagen models worldwide, Reuters said.

Under Singapore's environmental regulations, all vehicles need to comply with stipulated emissions standards, NEA said.