The European Union’s chief Brexit negotiator Michel Barnier has dismissed an aggressive tweet by the office of the British prime minister, saying that the offending tweet risked obstructing continued negotiations on the UK’s future relationship with the EU.

“I have no time to lose in polemics right now,” Barnier told the AFP news agency, responding to a tweet from Boris Johnson’s press office referring back to a post by Barnier in 2017.

“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 added, according to AFP.

The divisive tweet sent on Tuesday posted a slide apparently shared by the EU in 2017 referring to a Canada-style free trade agreement as being “the only available relationship for the UK”. The tweet went on to publicly question the EU’s Brexit point man Barnier, “now they say it’s not on offer after all […] what’s changed?”

The tweet is the latest salvo in the biggest bone of contention – the EU’s position that the UK must adhere to the economic bloc’s environmental, labour and tax standards if it wants to secure a free trade deal.

EU officials speaking to the AFP news agency denied that they had changed their negotiating position as suggested by the tweet. “It has always been very clear that a free trade deal is linked to a level playing field,” an EU official said, according to AFP.

The UK and EU had already traded blows earlier in the week when Britain’s chief Brexit negotiator David Frost gave a speech in Brussels describing how the UK’s desire to strip itself of EU rules was the point whole of Brexit.

Stefaan de Rynck, a top advisor to the EU’s Barnier, then told an audience at the London School of Economics that the UK must still follow some EU regulations if it wants to secure a new trade agreement by the end of the transition on 31 December.

UK immigration debate

The British government also faced criticism on Wednesday over its new immigration plans, aiming to stop “cheap labour from Europe”.

The proposed points-based system outlines plans to require each foreign worker to earn 70 points from a range of criteria including salary. Prospective migrants will be awarded 20 points for a salary of at least 30,820 euros and no points if they do not secure the required minimum.

Sectors such as health and social care, construction as well as hospitality could be hardest hit by the changes, according to the Confederation of British Industry. “Firms know that hiring from overseas and investing in the skills of their workforce and new technologies is not an 'either or' choice,” said CBI director-general Carolyn Fairbairn.

Interior minister Priti Patel brushed aside suggestions that jobs in the UK could be left vacant, telling Sky News that “it’s about time businesses started to invest in people in this country.”