The allegations relate to vehicles built at Nissan’s plant in Sunderland as, since 2014, South Korea’s emissions requirements for diesel vehicles have been based on the same Euro 6 limits which came into force for European markets last year. Petrol cars must comply with U.S. standards.

Jonathan Adashek, Chief Communications Officer at Nissan, said: “The testing and conclusions reached by the MOE are inconsistent with those of other regulators who have themselves carried out stringent testing.

“Authorities in the EU have concluded that the Nissan vehicles they tested – including the Qashqai – were fully compliant with homologation standards.”

Emission control systems are permitted to operate with reduced efficiency under specific circumstances – even during laboratory testing – provided these functions are to protect the engine or improve durability, and not specifically to recognise test conditions and alter settings to meet limits. The latter is defined as a ‘defeat device’, and is illegal.

The allegation follows investigations in Germany and the UK, the results of which were announced in April. These confirmed that nobody other than the Volkswagen Group had used defeat devices to pass emissions tests but adding that Euro 5 and Euro 6 vehicles are emitting, on average, six times more NOx than their respective limits in road use.

Although two versions of the Qashqai were included in this study, both were Euro 5 models which would have been ineligible to be sold in South Korea.

Following internal development work, which predates the Volkswagen scandal, Nissan’s alliance partner Renault announced last month that it will begin offering software upgrades for Euro 6 versions of the 1.5-litre diesel engine aimed at reducing NOx emissions in road use. Daimler has also said it will offer these upgrades for the A and B-Class, which use the same engine.

Adashek added: “We are in the process of responding to the MOE about their findings and will continue to work transparently with them so they clearly understand the situation regarding the Qashqai's engine system.”

Nissan has sold 814 Qashqais in South Korea, but the crossover is the UK’s fifth best-selling car to the end of April according to SMMT figures, with 23,140 sold.