Britain will find it far harder to negotiate a trade deal with the United States without the might of the EU behind it, a French minister has warned.

Photo: Javier Lizon / POOL / AFP

US President Donald Trump - after Boris Johnson secured his spot as Prime Minister in Britain's election in December - said the countries would be free to strike a "massive" new trade deal that could be "more lucrative" than any EU deal, after Brexit.

French trade minister Jean-Baptiste Lemoyne however told Reuters a mid-sized power like Britain would find it tough to negotiate alone with the world's biggest economy.

"I've seen the statements boasting about a great trade deal with the United States," Lemoyne said.

"But I think the British will come to realise how different it is to negotiate as part of a bloc like the European Union, which has 500 million consumers, than as a country of 60 million or so. The power dynamic is not the same."

Photo: AFP

Lemoyne also warned European negotiators against rushing into a "botched" deal because of the tight deadline before the end of the transition period at the end of the year when EU rules stop applying to the UK.

"We're going to have to work flat out," Lemoyne said. "What's certain is that content must prevail over timing. We can't afford to botch some issues.

"Talks will certainly be tough, but we can't give too much away or be negligent about certain rules that matter to us because there's a tight deadline."

Johnson has set a hard deadline to reach a new trade deal with the EU, betting that the prospect of another Brexit cliff-edge would force Brussels to move more quickly to seal an accord.

London also hopes it can secure a deal with the US before the presidential election in November.

Photo: AFP

French President Emmanuel Macron consistently took a hard stance on Brexit during the first phase of negotiations.

At the last EU summit in Brussels, he warned Britain against a deregulation of its economy, saying that would prompt the EU to shut off access to Britain's biggest export market.

The stakes are high for France, as Britain represents its biggest trade surplus as a destination for French wines, champagne, cars and drugs.

Lemoyne said Britain often did not have domestic alternatives, however, which should help the French strike a deal.

"We're lucky to have complementarities with Britain. I think these should be encouraged," he said.

- Reuters