In a letter to campaigners he promised that Europe was “committed to address this issue as a top priority in the upcoming negotiations” and that “our goal must and will be to create clarity as quickly as possible”.
The meeting in Brussels on 28 March comes just two weeks after the House of Commons rejected an amendment to the article 50 bill which sought to guarantee an early deal on the rights of EU citizens in the UK.
Among those meeting Barnier is Monique Hawkins, a Dutch woman who was told by the Home Office to “prepare to leave” after 24 years living in Britain, many of them with her British husband and their two children.
She has since received a permanent residency card but her case highlighted the stress and anxiety felt by the estimated 3 million EU citizens in the UK and 1.2 million British nationals settled in Europe.
Five representatives from grassroots organisation the3million will attend, along with three representatives of UK nationals living in Europe, including Jane Golding, a lawyer living in Germany who has been involved in a coalition of 12 groups across mainland Europe seeking to secure rights for Britons in the EU.
Nicolas Hatton, founder of the3million, said: “This raises the possibility of an early deal to secure our rights, which makes me really hopeful about the future.”
The letter, signed by Stefaan de Rynck, an adviser on Barnier’s taskforce on UK negotiations, reminds the groups that there can be no negotiations before notification of article 50, which is due before the end of March.
It also agrees with them that the protection of rights “must happen through an EU-wide process, and not bilaterally between EU countries and the UK”.
The tone of the letter is one of reassurance: “On behalf of Michel Barnier … We in the European commission fully understand the anxiety that you have experienced in the wake of the UK’s vote to leave the EU and the uncertainty that the outcome of the referendum has created.”
It points out that the European council “intends to adopt its guidelines for the negotiations quickly so that formal work with the UK [can begin] soon afterwards”.
The citizens delegation also has a meeting with the Department for Exiting the European Union on Monday.
Brexit secretary David Davis said this week that he was confident an early deal could be struck for both groups which would seek to define their rights to residency, pension and healthcare among other issues.
He said he hoped to get a heads of agreement with other EU leaders and the European commission, although this is unlikely to have legal standing until signed into an exit treaty.
“I will try to get an exchange of letters which makes absolutely plain what we think the outcome will be and should be and are determined to make,” he told the Brexit select committee.
Davis said his commitment was to secure a deal for Britons and for EU citizens and not to separate them in negotiations.
“The aim is make the whole package of EU and UK citizens together in one entity,” he said.
“All except one of the meetings I have had since the white paper with foreign ministers, it’s come up spontaneously as the first issue, and in that one [where it wasn’t] it was the second issue.
“They are concerned about their own citizens. They understand the complementarity. It is notable the noises in Brussels reflect that.”