French President Nicolas Sarkozy, who has laboured to improve French relations with Israel, said he "can't stand" Israeli Prime Minister Benjamin Netanyahu and called him a liar in a chat with President Barack Obama.

The conversation between Sarkozy and Obama was overheard by reporters last week at the Group of 20 summit in southern France, via headsets that were to be used for simultaneous translation of an upcoming news conference.

Obama, whose remarks were heard via a French translation, was not heard objecting to Sarkozy's characterization of Netanyahu. Through the interpreter, Obama was heard asking Sarkozy to help persuade the Palestinians to stop their efforts to gain UN recognition of a Palestinian state.

Several French-speaking journalists, including one from The Associated Press, overheard the comments but did not initially report them because Sarkozy's office had asked the journalists not to turn on the headsets until the press conference began, and the comments were deemed private under French media traditions.

A French website that analyzes media coverage of current affairs, Arret sur images, reported the fragments Tuesday.

Sarkozy's office would not comment Tuesday on the remarks, or on France's relations with Israel. The White House and Netanyahu's spokesman also said they had no comment.

In the remarks Thursday in Cannes, Sarkozy said: "Netanyahu, I can't stand him. He's a liar."

According to the French interpreter, Obama responded, "You are sick of him, but I have to work with him every day."

The journalists heard only fragments of the leaders' conversation.

May complicate peace process

Since becoming president in 2007, Sarkozy has strengthened French ties with Israel while also seeking to use France's traditional good relations with Arab allies to encourage peace talks.

His latest comments reflect his increasing frustration with Netanyahu, and may complicate French efforts toward Mideast peace.

The overheard remarks by Sarkozy and Obama were prominently covered in Israel, where Sarkozy — whose maternal grandfather was Jewish — is widely perceived as a friend, in striking contrast to some of his predecessors, including Jacques Chirac, whom Sarkozy replaced in 2007.

Restarting negotiations Mediators will hold separate talks with the Israelis and Palestinians in a bid to relaunch peace talks after a series of setbacks that have damaged negotiations, the U.S. State Department said Tuesday. Senior diplomats from the U.S., UN, Russia and European Union will meet on Friday in Jerusalem with Israeli and Palestinian negotiators, department spokesman Victoria Nuland said. The group, known as the Quartet, is trying to bring the two sides back to the table with the goal of reaching a deal by the end of next year.

Israel has had a fraught up-and-down relationship with France. The country was an early supporter of the Jewish state, selling it arms and planes and helping it develop a nuclear reactor. But the relationship soured under Charles de Gaulle, perceived as having abandoned Israel before the 1967 war.

"There has been improvement of the relationship since Sarkozy took over," Avi Pazner, who was Israel's ambassador to France in the 1990s, said Tuesday. "He has shown himself as a friend of the state of Israel."

In comments at the G20 last week, Sarkozy said that if Israel's existence is threatened, "France will not stand by with arms crossed."

Netanyahu, meanwhile, is a controversial figure even at home. He is widely seen as divisive, and is regularly pilloried by the centre-left opposition who say he prefers settlement construction in the West Bank to peace talks.

The often blunt Sarkozy has shown little patience with Israeli hardliners, and two years ago urged Netanyahu to fire his outspoken foreign minister, Avigdor Lieberman. In a private meeting, Sarkozy told Netanyahu that "you must get rid of that man," according to two officials.

This September, the French leader tried to head off the Palestinians' request for membership in the United Nations with a last-minute effort to revive peace talks.

But France then surprised Washington and other observers by voting last week in favour of Palestinian membership in UNESCO, the UN cultural and educational agency.