The president of the European Commission was keen to reassure the billionaires' retreat in Davos: a deal is in the works to head off fears of a trans-Atlantic trade war.

But back in the EU capital Brussels on Thursday, Ursula von der Leyen's promise of some kind of agreement "in a few weeks" left officials scratching their heads.

"I can't understand it, to be honest," German MEP Bernd Lange, who chairs the European Parliament's trade committee, told AFP.

"I spoke yesterday to some commission high-level staff and there was also no understanding of this speech."

Several sources at the European Council, which represents EU member states, also admitted that they were perplexed.

And no member state diplomat consulted by AFP had been forewarned of any deal by the Commission. "She speaks only for herself," one declared.

One said Von der Leyen's Davos visit had not been discussed at the regular EU ambassadors' meeting, but that trade commissioner Phil Hogan's less positive trip to Washington had come up.

"Unfortunately, no one knows anything," said a diplomat from an important EU power, keenly aware of US President Donald Trump's threats to impose harsh trade tariffs.

"There's a plan to put in place a new packet of measures to make peace, but no one knows what's in it."

And, asked about prospects of a deal in Davos, French Finance Minister Bruno Le Maire recalled President Emmanuel Macron's previously tough position.

"We don't want to sign a trade deal with a country that rejects the Paris climate accord," he declared, referring to Trump's decision to ditch the pact.

What could be going on, then? European experts said that rather than a full trade deal, Brussels may be aiming for a political declaration between Trump and von der Leyen.

The former German minister's predecessor at the commission, Jean-Claude Juncker, won such a truce in the Oval Office in July 2018, but without resolving underlying concerns.

And Trump has since gone on the offensive again, threatening crippling tariffs on EU car exports and countermeasures against digital taxes planned by European capitals.

Von der Leyen is expected to head to Washington in the coming weeks to meet Trump, but last week's trip by Hogan was not seen here as having been very promising.

Since Trump came to office with a mission to rebalance trade global relations he has imposed steel and aluminium tariffs and threatened German cars and French wine. afp