|Indiscreet remarks by Obama, left, and Sarkozy are likely to cause embarrassment for both [Reuters]
French President Nicolas Sarkozy called Binyamin Netanyahu, Israel's prime minister, a "liar" in a conversation with his US counterpart, Barack Obama, accidentally broadcast to journalists at last week's G20 summit in the French resort of Cannes.
"I cannot bear Netanyahu, he's a liar," Sarkozy told Obama, unaware that the microphones in their meeting room had been switched on.
Reporters in a separate location listened in to a simultaneous translation as Obama responded, according to a French interpreter: "You're fed up with him, but I have to deal with him even more often than you."
Al Jazeera's Jacky Rowland in Paris, who covered the Cannes summit, said: "This is was one of those diplomatic gaffes that can befall even the most powerful and the most rich in this era of radio microphones."
Rowland said the two leaders apparently had already had their microphones for the press conference attached to them, when they were having a private one-on-one conversation just before the press conference.
"Journalists in the hall had already been given the simultaneous translation box, and some of them had plugged their own personal headphones in and they were able to hear ... these indiscreet undiplomatic remarks," she said.
The gaffe is likely to cause great embarrassment to all three leaders as they look to work together to intensify international pressure on Iran over its nuclear ambitions.
The conversation was not initially reported by the small group of journalists who overheard it because it was considered private and off-the-record. But the comments have since emerged on French websites and have been confirmed by the Reuters news agency.
Jay Carney, the White House press secretary, declined to comment on the conversation when asked by reporters travelling with Obama to an event in Philadelphia.
Obama's apparent failure to defend Netanyahu is likely to be capitalised on by his Republican foes, who are looking to unseat him in next year's presidential election. They have portrayed him as hostile to Israel, Washington's closest ally in the Middle East.
Pressuring Netanyahu risks alienating Israel's strong base of support among the US public and in Congress. Netanyahu's office declined immediate comment.
Obama and Netanyahu have had a rocky relationship as US efforts to broker a Middle East peace deal have floundered, with the US president openly criticising illegal settlement building in the occupied Palestinian territories.
It was unclear why exactly Sarkozy had criticised Netanyahu.
However, European diplomats have largely blamed Israel for the breakdown in peace talks and have expressed anger over Netanyahu's approval of large-scale settlement building in East Jerusalem.