Javad Zarif, the Iranian foreign minister, unexpectedly flew into Biarritz on Sunday in a dramatic twist to a G7 leaders summit that is already riven by divisions over Russia, China and trade.

Mr Zarif, who went straight into talks with French officials after his surprise arrival on an Iranian government Airbus, showed up as French President Emmanuel Macron attempted a high-risk diplomatic gambit to defuse a confrontation that has brought Iran and the United States to the brink of war.

His presence caused immediate confusion in diplomatic circles, with a White House official saying that Donald Trump, who dined with other G7 leaders in Biarritz on Saturday night, was not informed in advance.

Mr Trump's administration placed Mr Zarif under sanctions last month.

But a French diplomatic source said Mr Macron informed Mr Trump of the Iranian foreign minister’s visit when the two presidents had lunch on Saturday. Mr Macron then told the other leaders during dinner on Saturday night.

“There was a very substantial conversation among the G7 leaders,” the source said. The source added that the French and Iranian foreign ministers were also discussing “regional issues and Iran’s missile programme”.

“We are working in total transparency with our US partners,” he said.