Britain hit back Friday at French criticism of its economy as deputy premier Nick Clegg told France's prime minister the comments were "simply unacceptable".
Clegg told Francois Fillon to "calm the rhetoric" after France had further fuelled the row by describing the state of Britain's economy as "very worrying".
The French attack was sparked by a warning from US credit ratings agency Standard and Poor's that it could strip France of its triple-A rating as a result of the eurozone crisis.
In response, Christian Noyer, the governor of the French central bank, suggested on Thursday that the ratings agencies should consider downgrading Britain instead, before Fillon added to the criticism of the British economy.
In an attempt to explain his remarks, Fillon called Clegg from Brazil, where he is on a visit, "to clear up misunderstandings", a Fillon aide told AFP.
Clegg's office said: "Fillon made clear it had not been his intention to call into question the UK's rating but to highlight that ratings agencies appeared more focused on economic governance than deficit levels."
Britain's deputy prime minister "accepted his explanation but made the point that recent remarks from members of the French government about the UK economy were simply unacceptable and that steps should be taken to calm the rhetoric".
Both men agreed they would speak again shortly to discuss "cooperation".
Cameron's Downing Street office said Clegg was "absolutely right", and the French remarks were "not helpful in any way", according to the BBC.
Fillon's conversation with Clegg came after he told reporters that ratings agencies had ignored the state of Britain's finances.
"Our British friends are even more indebted than we are and have a higher deficit but the ratings agencies do not seem to notice this," Fillon said.
The cross-Channel row comes after Britain clashed with France at a dramatic European Union summit last week when Prime Minister David Cameron refused to join members of the eurozone currency bloc in a new fiscal pact.
That prompted French President Nicolas Sarkozy to declare there are now "two Europes".
Before the attempt by Fillon to calm the waters, French Finance Minister Francois Baroin picked up the issue, claiming the French economy was in better shape than Britain's.
"It's true that the economic situation in Great Britain is very worrying and that we prefer being French rather than British on the economic front at the moment," Baroin told Europe 1 radio.
"We don't want to be given any lessons and we don't give any," he said.
Earlier Friday, a spokeswoman for Cameron said Britain had "a credible (economic) plan endorsed by numerous international organisations.
"The bond yields underline the credibility of that plan," she said, in reference to the cost to Britain of borrowing to fund its debt, which compares favourably with the benchmark German rate.
The British press slammed the French comments, with The Sun tabloid saying: "You find out who your friends are in a crisis".
"We shouldn't be surprised, then, when the head of the Bank of France tries to better his country's economic position by sabotaging ours."
The Daily Telegraph broadsheet said "France declares war of words on Britain".
France's state statistics agency warned the country will fall into a brief recession through to the first quarter of 2012.
Analysts said French officials seemed to be trying to deflect attention from the country's own economic concerns.
Fitch Ratings on Friday affirmed France's triple-A rating on its debt, but revised its long-term outlook on the rating to "negative" from "stable".
"The intensification of the Eurozone crisis since July constitutes a significant negative shock to the region and to France's economy and the stability of its financial sector," Fitch said in a statement.