An ally of French President Francois Hollande has compared Prime Minister David Cameron to French far-right leader Marine Le Pen, over his "nationalistic" refusal to pay £1.7bn in EU budget back payments.
The senior source in the French government described the PM's stance in refusing to pay the £1.7bn bill, charged because the UK economy stronger than previously thought following a review of national incomes, was "nationalistic" and "Byzantine".
The source said Cameron had shown "no European solidarity" by insisting he will not meet the demand.
Cameron reacted angrily during a news conference at an EU Summit in Brussels last month, thumping a lectern with his hand in a show of anger that some EU leaders found at odds with the more collegial atmosphere in the summit room.
Cameron said: "It's an appalling way to behave. I'm not paying that bill on 1 December. If people think I am, they've got another thing coming. It is not going to happen."
In comments that will spark outrage in Downing Street, the source compared Cameron to Le Pen, who leads the far-right Front National party in France.
The senior French government figure told the Telegraph that Cameron's behaviour had been "completely crazy".
"Marine Le Pen would behave like that in France, because it is the best way to show that there is no European solidarity. It's [a sign of] the Byzantine Empire, where everyone is after his own piece of meat.
"You can fight for your budget, you can put pressure on Europe, and be very tough on the Commission. In that sense [Cameron] is right.
"You can say: 'It's unacceptable, we have a huge problem with it, we demand an audit from the parliament regarding the Commission.' You can call for more simplification. But it is nationalistic, even in the body language, to say: 'It doesn't suit us.'"