Brussels (Belgium) (AFP) – Brussels is headed for a showdown this week over the European Union's free-trade deal with South American bloc Mercosur, after France launched a last-ditch effort to derail the signing of the landmark accord.

European Commission chief Ursula von der Leyen is due in Brazil on Saturday to sign the agreement, which, 20 years in the making, would create the world's biggest free-trade area.

First though she needs to get approval from the EU's member states -- despite frontal opposition from key power France which warned Sunday the conditions were not in place for a vote.

President Emmanuel Macron's office said he had reached out to von der Leyen to personally request a delay.

But the commission, which steers trade policy for the EU, reiterated Monday it still expects the deal to be signed by the end of the year.

"Signing the deal now is a matter of crucial importance -- economically, diplomatically and geopolitically," said a spokesman for the EU's executive.

Wrangling is set to go down to the wire, with up to 10,000 farmers planning to descend on the Belgian capital to vent their anger at the deal during a leaders' summit Thursday and Friday.

The deal will allow the EU to export more vehicles, machinery, wines and spirits to Latin America, while facilitating the entry of South American beef, sugar, rice, honey and soybeans into Europe.

Fearing negative fallout for its agricultural sector -- a concern shared by farmers in Poland and elsewhere -- France has been clamouring for robust safeguard clauses, tighter import controls and more stringent standards for Mercosur producers.

Paris faces an uphill battle to block the treaty, which only needs support from a weighted majority of EU countries to pass.

Powerhouse Germany, Spain and the Nordic countries are strong backers of the pact, eager to boost exports as Europe grapples with Chinese competition and US tariffs.

A source in the European Commission said the time to close the deal was "now or never".

But disagreements in a key week when the 27-nation bloc also has to decide on the divisive issue of using frozen Russian assets to aid Ukraine are leaving some uneasy.

"If there is no compromise this week, we risk a serious European crisis. It will be a major failure for the commission, for Germany and for Spain," said one European diplomat.

A time for the member state vote is still to be determined.

Complicating matters, the European Parliament is to vote Tuesday on "safeguard" measures aimed at reassuring farmers -- and placating France.

EU states have already approved the safeguard clause in question, but lawmakers may decide to strengthen it further.

In another gesture aimed at Paris, the commission last week announced tighter checks on farm imports to ensure they meet EU standards, and pledged to update rules on pesticide residues to prevent banned substances entering via imports.

Von der Leyen intends to join the leaders of Mercosur members Brazil, Argentina, Paraguay and Uruguay in Foz do Iguacu, home of the famed Iguacu waterfalls, for the signing.

Even if she seals the deal in time to fly there, the battle will not be over.

The European Parliament must still give its final approval to the accord, likely in early 2026. Insiders expect a close vote, with national interests weighing heavily.

"All the French will vote against, most of the Poles too," said one parliamentary source, expecting opposition to run across party lines in those countries.

Add parliament's far-left and far-right groups, which broadly dislike the deal, the source said, and you reach around 300 of the assembly's 720 lawmakers -- which could make for an uncomfortably tight vote.