In the article, translated by Automotive News Europe, German transport minister Alexander Dobrindt said the European Commission must ensure Fiat vehicles that do not comply with pollution regulations are pulled from sale.
"The Italian authorities have known for several months that Fiat, in the opinion of our experts, uses illegal shut-off devices," he said.
"Fiat has so far refused to participate in the clarification [of the matter, and the commission] must consequently ensure that a recall is organised for the Fiat vehicles."
The commission has expressed concerns about the Fiat 500X and several other models, which are believed to be fitted with shut-off devices that throttles back the emissions treatment system during government testing.
Above, Top and Below: Fiat 500X
Environmental lobby group DUH also claims the 2.0-litre turbo-diesel version of the 500X releases excessive amounts of NOx – though several other models including versions of the Opel Zafira, Renault Espace and Mercedes-Benz C-Class were also claimed by the firm to emit extreme overruns of the toxic gas.
Germany's Federal Motor Transport Authority (KBA) also found that the emissions treatment of an unnamed Fiat model was throttled back after 22 minutes – the normal duration of regulatory tests is around 20 minutes.
Meanwhile, Italy's deputy transport minister, Riccardo Nencini labelled the German government's comments as "incomprehensible", adding that the Italian government is cooperating with the commission.
"We have repeatedly asked Italian authorities to come forward with convincing answers as soon as possible," the Commission said in a statement.
"The EU Commission is now doing exactly what has been demanded for a long time: it's talking again with the Italians."
A previous report by Bild am Sonntag claims automotive supplier Bosch informed German investigators that Fiat was using a mechanism that virtually disabled exhaust filters.
However, it's unknown whether these circumstances are inline with the 'thermal window', which allows manufacturers to throttle back emissions management systems to protect the engine from condensation and other damage while also improving performance and increasing service intervals.
This latest report comes after Fiat Chrysler Automobiles (FCA) was accused by the US Environmental Protection Agency (EPA) of installing defeat devices in its 3.0-litre turbo-diesel engines.
Following the accusations, FCA's CEO, Sergio Marchionne, lashed out at EPA for its claims which he says are "absolute nonsense".
"There is nothing in common between the Volkswagen reality and what we are describing here," he said, referring to Volkswagen's 'dieselgate' saga.
Marchionne added that anyone who disagreed must be "smoking illegal material".
Above: Volkswagen's Dieselgate saga has changed perceptions of diesel-powered vehicles globally
Just last week Volkswagen agreed to plead guilty to three criminal charges for its emissions cheating scandal, also agreeing to pay $4.3billion in fines. Additionally, six Volkswagen executives have been charged by the FBI.
In terms of local impact, Australian owners of the Fiat 500x are unaffected as the diesel engine isn't offered here.
The Italian brand actually doesn't sell any diesel-powered models locally with the exception of its commercial van range, which isn't mentioned in the European reports.
Stay tuned to CarAdvice for more updates.