BRUSSELS (AFP) - The EU's Brexit negotiator Michel Barnier on Wednesday (Feb 19) expressed irritation at a combative tweet from British Prime Minister Boris Johnson's office claiming that Brussels is shifting objectives in upcoming trade talks.

"I have no time to lose in polemics right now. I recommend, on both sides, that we remain calm and face the reality, the truth and the economic, social and human consequences of Brexit," Barnier told AFP.

The offending tweet republished a two-year-old slide used by Barnier displaying the trade options available to the UK according to various negotiating red lines.

Above it, Johnson's press office wrote: "In 2017, the EU showed on their own slide that a Canada-style FTA (free trade agreement) was the only available relationship for the UK. Now they say it's not on offer after all. Michel Barnier what's changed?"

One European official, speaking to AFP on condition of anonymity, described the post from the Number 10 press office as "deeply false, dishonest".

The tweet referred to the biggest point of contention in the negotiations: the EU's insistence that Britain must hew to the bloc's labour, environmental and tax standards - to ensure a "level playing field" - if it wants a free trade pact.

Although that demand has been made in EU documents and in a non-binding political declaration Britain signed last year, Britain is baulking at having to abide by EU rules now that it is no longer part of the bloc.

"It's wrong to say we've changed our position. It has always been very clear that a free trade deal is linked to a level playing field," the EU official said, adding that the British tweet was received "very negatively" in Brussels.

HARDENING TONE

Another official, also speaking on condition of anonymity, said the tweet was "more meant for the internal debate in the United Kingdom," where several business sectors want to keep close trading ties with the EU.

That official noted that each FTA is different, and Britain's situation is unique because it was within Europe with an economy that was deeply intertwined with its EU neighbours.

"Imports from Canada, Japan and South Korea together are less than UK imports," the official said.

Britain left the EU at the end of last month but enjoys a transition period through the end of this year, during which it is allowed to trade like an EU member.

That period is meant to provide space to negotiate a deal on a future relationship. But the tone between Brussels and London has been deteriorating, with Britain increasingly saying it is ready to eschew a trade deal rather than cede "sovereignty" to the EU.

The British government's own figures show that the UK economy will suffer from Brexit even if a trade deal would mitigate that to a degree. Without one, potential growth would be crimped further.

Some of the back-and-forth happening now is seen as chest-beating before the negotiations begin next month.