The socialist Royal went on the offensive during the debate watched by more than 20 million viewers, challenging her rightwing opponent on his record as a member of the outgoing government and angrily accusing him of "political immorality."

Sarkozy, who leads in opinion polls, said he was "suprised by the degree of aggressiveness" shown by his rival during the exchange that lasted two and a half hours, saying it showed "a form of intolerance."

"It is revealing of the reactions that can come from some quarters of the left who consider anyone who does not share their ideas as illegitimate," he said in a radio interview.

Both candidates sought to address their weaknesses during the debate: Royal had to dispel doubts about her presidential stature while Sarkozy faces concerns over his hyper-active personality.

Royal, who wants to become France's first woman president, said Sarkozy "did not dare" repeat during the debate some of the accusations he had directed at her during the campaign.

He "reminds me of those children who kick and then cry out to make believe that it was their playmate who hit first," Royal told French radio.

The most fiery outburst came in an exchange about places for handicapped children in ordinary schools.

Royal accused Sarkozy of "becoming teary-eyed" over the plight of handicapped children when it was his government that had dismantled Socialist measures guaranteeing a place for the disabled in ordinary schools.

"This is the height of political immorality," said an outraged Royal.

Sarkozy retorted: "I don't question your sincerity, don't question my morality ... You lose your temper very easily."

"To be president of the republic, you must remain calm," Sarkozy insisted.

"I have not lost my cool. I am angry and there is anger that is perfectly healthy," Royal hit back, waving an accusatory finger.

Commentators said Sarkozy scored points for keeping his cool while Royal won kudos for her combativeness in the face-off ahead of Sunday's vote.

"Nicolas Sarkozy did not lose. But Segolene Royal won," wrote the left-leaning Liberation newspaper, whose front page featured a closeup of Royal's face, with clenched jaw, and the headline: "Combative."

But the rightwing Figaro daily said Royal had been "often vague, at times aggressive" and that "at the end of the end, Sarkozy's self-control shone through."

"She won in terms of style, he won in terms of substance. They both held their ground," commented pollster Roland Cayrol.

"I would have to say that Sarkozy won," said veteran political commentator Alain Duhamel. "Not because he delivered a knock-out punch, but because he got more points."

The encounter could be decisive in determining the choice of nearly seven million voters who backed centrist Francois Bayrou in the first round on April 22, and who now hold the key to victory.

Bayrou was quoted in Le Monde as saying that Royal "had done rather well" in the debate and announced "I will not vote for Sarkozy" even though he did not explicitly throw his support behind Royal.