Are we allowed to talk about glass houses?

French Prime Minister Sarkozy must see himself as a latter-day George Washington who cannot tell a lie or, at least, someone who can call other people liars with a straight face. Or so it would seem from the story that was suppressed by faithful journalists at first but has surfaced on French websites and has now been confirmed by Reuters.

French President Nicolas Sarkozy branded Israeli Prime Minister Benjamin Netanyahu "a liar" in a private conversation with U.S. President Barack Obama that was accidentally broadcast to journalists during last week's G20 summit in Cannes.

"I cannot bear Netanyahu, he's a liar," Sarkozy told Obama, unaware that the microphones in their meeting room had been switched on, enabling reporters in a separate location to listen in to a simultaneous translation.

"You're fed up with him, but I have to deal with him even more often than you," Obama replied, according to the French interpreter.

The technical 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 can be confirmed by Reuters.

Obama's apparent failure to defend Netanyahu is likely to be leapt on by his Republican foes, who are looking to unseat him in next year's presidential election and have portrayed him as hostile to Israel, Washington's closest ally in the region.

It is also, by a strange coincidence the only democracy in the region but that is not likely to worry either Sarko or Obama.

However, the behaviour of journalists who decided that this particular conversation was private and off the record and was, therefore, not to be broadcast to all and sundry is curious. Would it have happened with other politicians in slightly different circumstances? Somebody broke ranks, clearly.

Netanyahu's office refused to comment, presumably because they could not stop laughing long enough.