The case came before the EU Court of Justice (CJEU) after Volkswagen challenged a 5 million euro ($5.4 million) Italian antitrust fine levied in 2016 for its misleading advertising about its cars fitted with illegal defeat devices.

Volkswagen separately paid a 1 billion euro German fine in 2018, with the scandal costing it more than 32 billion euros in refits, fines and legal costs so far.

The Italian court in its 2019 ruling rejected Volkswagen's appeal, saying there was no double jeopardy involved as the Italian fine derived from a different legal basis.

Volkswagen took its case to the Italian Council of State which then sought advice from the CJEU.

Advocate General Manuel Campos Sanchez-Bordona said in a non-binding opinion it could be a case of double jeopardy, which means that people cannot be charged twice for the same offence and which ensures legal certainty and equality.

"The two proceedings relate to the same legal person (Volkswagen), and that the facts penalised are identical in substance and time," he wrote.

He said there appeared to be no coordination between the Italian and German authorities to avoid double jeopardy.

"Volkswagen cannot be penalised in Italy for 'Dieselgate', after having been penalised in Germany, if there has not been sufficient coordination between the penalty proceedings of both States," Campos Sanchez-Bordona said.

The CJEU, which usually follows four out of five recommendations, will rule in the coming months.

The case is Opinion in Case C-27/22 Volkswagen Group Italia and Volkswagen Aktiengesellschaft.

($1 = 0.9210 euros)

(Reporting by Foo Yun Chee; Editing by Alexander Smith)

By Foo Yun Chee