Far-right candidate Marine Le Pen and centrist Emmanuel Macron have clashed over France's economy, security and Europe in an ill-tempered televised debate ahead of Sunday's runoff vote for the presidency.

The two went into the only head-to-head debate before the election with opinion polls showing Macron, 39, maintaining a strong lead of 20 percentage points over the National Front's Le Pen, 48, in what is widely seen as France's most important election in decades.

The two candidates, seated opposite one another at a table in the television studios on Wednesday, mapped out diametrically opposed visions for France. Macron calls for liberal reforms to kick-start the French economy, while Le Pen rails against the loss of French jobs through off-shoring and would adopt protectionist trade measures.

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For Le Pen, the debate, watched by millions, was a last major chance to persuade voters of the merits of her programme, which includes cracking down on illegal immigration and ditching the euro currency.

Macron accused her of not offering solutions to problems such as France's chronic unemployment.

In angry exchanges, Le Pen played up Macron's background as a former investment banker and economy minister, painting him as a continuation of the outgoing unpopular socialist government.

"Mr Macron is the candidate of globalisation gone wild, of Uberisation, of precariousness, of social brutality, of war by everybody against everybody ... of the butchering of France by big economic interests," she said, referring to the gig economy typified by US app-based taxi service Uber.

Macron hit back by calling Le Pen a liar, saying she was talking nonsense and that her rhetoric lacked substance.

On unemployment, Macron told Le Pen: "Your strategy is simply to tell a lot of lies and just to say what isn't going right in the country."

Barbs over security

But the sharpest exchange was over national security, a sensitive issue in a country where more than 230 people have been killed in attacks since 2015.

Le Pen accused Macron of being complacent over security. "You have no plan [on security] but you are indulgent with Islamist fundamentalism," she said.

Macron retorted that "terrorism" would be his priority if he is elected and accused Le Pen of being simplistic.

"What you are proposing is snake oil," he said, referring to her proposals to close France's borders.

"I will lead a fight against Islamist terrorism at every level. But what they are wanting, the trap they are holding out for us, is the one that you offer - civil war," he said.

Battle over Europe

Turning to the European Union, Le Pen said Macron as president would allow France to be crushed by its economically powerful neighbour Germany.

"France will be led by a woman, either me or Mrs Merkel," she said, referring to the German chancellor.

Le Pen wants to hold a referendum on whether France should stay in the EU, while Macron is fervently pro-Europe.

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Le Pen set out her plans - criticised by economists - to scrap the euro for daily purchases and return to the franc, although the euro would remain the currency "for central banks and companies".

Macron responded: "The euro is important. It's not just a policy."

Al Jazeera's Natacha Butler, reporting from the debate in Paris, said Macron had put in a strong performance.

"He really has looked very relaxed, very confident, and his strategy has really been to pull up the far-right Marine Le Pen on being too vague on policy, being too vague on detail, and he has really managed to get her on the back foot."

Butler said Le Pen had, as expected, attacked Macron and painted him as the candidate of the bankers and herself as the candidate of the workers.

"But she's been quite taken aback by Macron, who's been quite relentless in trying to pick her up on these points of policy and often she's been left there not really being able to answer," said Butler.

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More than 20 million viewers out of an electorate of close to 47 million were expected to tune in to the two-and-a-half-hour debate.

Macron finished only three points ahead of Le Pen in the first round on April 23, but he is widely expected to pick up the bulk of votes from the socialists and the centre-right whose candidates were eliminated.

Though Le Pen has a mountain to climb, the campaign has been packed with surprises.

Le Pen has secured a degree of acceptance for the once-pariah party by softening its image in an attempt to dissociate it from past xenophobic associations.

If Macron wins, one of his immediate tasks will be to build a parliamentary majority in follow-up elections in June to push through his programme.

Macron heads a fledgling movement called En Marche! (Onwards!) which has no representation in parliament.

A poll for Les Echos newspaper by OpinionWay-SLPV Analytics suggested Macron's party was set to emerge as the largest with between 249 and 286 seats in the 577-seat lower house, while the National Front was tipped to win 15 to 25.

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Source: Al Jazeera and news agencies