The row over French expulsions of Roma communities has erupted in a slanging match at an EU summit in Brussels.
French President Nicolas Sarkozy, incandescent over an attack on France and its deportation policy levelled this week by EU Justice Commissioner Viviane Reding, said he could not allow his country to be the victim of "outrageous" insults.
The controversy, which threatened to overwhelm a summit devoted to foreign policy and trade, spilled over at a leaders' lunch when President Sarkozy confronted Commission President Jose Manuel Barroso.
"It is outrageous that I come here and have to defend the honour of France," said President Sarkozy, before launching a broadside at Mrs Reding, who slammed the deportation of Roma minorities as a "disgrace".
Earlier this week Mrs Reding said: "I personally have been appalled by a situation which gave the impression that people are being removed from a member state of the EU just because they belong to a certain ethnic minority. This is a situation I had thought Europe would not have to witness again after the Second World War."
Her fellow Commissioners have supported her attack on expulsions on the basis of ethnicity but distanced themselves from her remarks on the Second World War - remarks she apologised for on Wednesday.
But President Sarkozy was not satisfied, insisting there had been no illegal expulsions based on ethnicity and insisting at a summit press conference that everyone - Commissioners and EU leaders - fully shared his outrage at the attack on a founding EU member state.
A spokesman for President Barroso afterwards insisted that was not the case, adding: "President Sarkozy does have a case to answer. No one supports President Sarkozy on the substance of the issue. There was a huge row over lunch with President Barroso insisting that he had a job to do of upholding EU laws on the free movement of its citizens and he would continue to do it. We will continue to consider whether to take legal action against France. That work is going on."
Prime Minister David Cameron, keener to trumpet success in agreeing fast-track proposals for long-term substantial aid to Pakistan and an accord on EU trade with South Korea, acknowledged only that the conversation over lunch had been "lively".
Asked his views on the Roma row, he said: "It is important that countries respect the law, but it is also important that they are able to take action to remove people if there is a problem of people behaving illegally. But people (Mrs Reding) also have to choose their words carefully. The Commission has a role to uphold the law, in a responsible way."