European Commission chief Jose Manuel Barroso on Monday compared France's Socialist leaders to the far-right in a war of words just days ahead of an EU summit where the increasingly bitter spat is set to be a major talking point.
In a blunt reply to criticism from Paris that reflects growing tensions in a European Union still struggling to recover from a devastating economic crisis, Barroso also accused France of using Europe as a "scapegoat" for troubles at home.
"It would be good if some politicians understood that they will not get very far by attacking Europe and trying to turn it into a scapegoat for their problems," Barroso said, stressing that he had been wilfully misunderstood by critics.
"Some left-wing nationalists have exactly the same views as the far right," he said in a scathing riposte to comments by French Industrial Renewal Minister Arnaud Montebourg who had accused Barroso of fuelling the rise of the far right.
The Commission also said in a statement that French leaders should defend Europe "against nationalism, populism and jingoism" instead of "attacking globalisation."
The row has its roots in France's bid to protect the European film and television industry from Hollywood dominance by stalling free-trade talks with the United States, but has escalated into a broader dispute over the European project.
Barroso had branded France's move to block the historic trade talks as "reactionary," igniting fury in Paris.
President Francois Hollande said he simply did not believe that Barroso could have made the comment while his Culture Minister Aurelie Filippetti said the remarks were "absolutely lamentable".
Hollande last month publicly warned the Commission it could not dictate France's economic policies.
Commission officials say the French sniping is unfair because they only implement the policies that EU member states agree on and which France was instrumental in creating.
Europe is "paralysed," Montebourg told France Inter radio.
"It does not respond to any aspirations of the people on the industrial front, on the economic front, on the budget front, and in the end that plays into the hands of all the ... anti-Europe parties in the EU," he said.
"Mr Barroso is the fuel of the National Front," he said, referring to the French far-right party that scored strongly in a by-election on Sunday that was narrowly won by the main centre-right opposition.
"I think the main cause of the rise of the National Front is related to the way in which the EU today exerts considerable pressure on democratically elected governments," he said.
But European Commissioner Michel Barnier, also a Frenchman, rubbished Montebourg's claims as "false and absurd."
"I've had it up to here with this and I say that with a degree of anger," Barnier said on Monday.
"I've had enough of hearing ministers in my country, politicians from left and right, saying that it is all somebody else's fault."
The dispute comes at a highly sensitive time for the EU.
The Dutch government said on Friday that the time of "an ever closer union" in Europe is over, laying out a list of policy areas that it said should be left to member states rather than Brussels.
British Prime Minister David Cameron has also called for powers to be wrested back from the European Union and for Britain's future membership to be put to a referendum.