The European Union will not step back “one millimetre” from defending the rights of EU citizens during Brexit negotiations, the president of the European Parliament has said.

Antonio Tajani said EU citizens in Britain were “still facing as much uncertainty now as they did when the British government formally triggered Article 50 in March”.

3.6 million EU citizens living in Britain, or around 6 per cent of the UK population, face uncertainty about the arrangements for them once Britain leaves the EU – a situation also faced by hundreds of thousands of British citizens living abroad in other EU countries.

“The EU will not step back one millimetre from its position in defence of the rights of European citizens,” Mr Tajani said, after a meeting with Jean-Claude Juncker in Brussels.

“First of all we will have to agree on the three crucial points... then we will talk about the rest.”

Brussels has insisted that citizens’ rights, as well as the issue of the Northern Ireland border and how much Britain owes the EU, must be settled before talks on trade and the future UK-EU relationship begin.

The Home Office has apparently intensified alarm among some EU citizens by erroneously sending out letters wrongly telling people to leave the country, according to repeated media reports.

The parliament president’s comments come amid reports the UK is trying to bypass chief negotiator Michel Barnier’s team at the Commission and speak directly to member states about trade first – a suggestion torpedoed by EU officials this morning.

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The third round of EU talks will come to a close on Thursday, after days of difficult discussions between the two sides.

The president’s comments come after Mr Barnier said the UK must start negotiating “seriously” and that he was “worried” about the UK’s “ambiguity” on certain issues.

Mr Juncker himself also said this week he did not believe preparation the UK had done to outline its position had been “satisfactory”.

Brexit: the deciders Show all 8 1 /8 Brexit: the deciders Brexit: the deciders European Union's chief Brexit negotiator, Michel Barnier Getty Brexit: the deciders French President Emmanuel Macron Getty Brexit: the deciders German Chancellor Angela Merkel Reuters Brexit: the deciders Commission President Jean-Claude Juncker EPA Brexit: the deciders The European Parliament's chief Brexit negotiator Guy Verhofstadt Getty Brexit: the deciders Britain's Prime Minister Theresa May Getty Images Brexit: the deciders Britain's Chancellor of the Exchequer, Philip Hammond PA Brexit: the deciders After the first and second appointed Brexit secretaries resigned (David Davis and Dominic Raab respectively), Stephen Barclay is currently heading up the position PA

Mr Tajani, an MEP from Silvio Berlusconi’s centre-right Forza Italia party, added: “A potential agreement will have to be approved by the European Parliament and our priorities have been consistently clear from the outset: defending the rights of EU citizens, preserving the achievements of the Good Friday Agreement and ensuring that the UK fully honours its financial commitments.