French President Nicolas Sarkozy called Israeli Prime Minister Benjamin Netanyahu a "liar" in remarks to US President Barack Obama overheard by journalists."I can't stand him any more, he's a liar," Mr Sarkozy said in French.
"You may be sick of him, but me, I have to deal with him every day," Mr Obama replied.
The exchange at the G20 summit was quoted by a French website, Arret sur Images, and confirmed by other media.
The remarks - during a private conversation - were overheard by a few journalists last week but were not initially reported, the BBC's Christian Fraser in Paris says.
Journalists at the bilateral press conference had been handed translation boxes but had been told not to plug in their headphones until the backroom conversation had finished. But those who did heard the revealing comments.
It can be that this will harm Obama's position. Both he and Sarkozy were right, though. It's nice to recall this tape, filmed in 2001 without Netanyahu's knowledge.
But maybe it is not necessary to show this video. His speeches - on the record - are telling enough. Like this one he held in the American Congress in May 2011.