THERESA May’s bid to clinch a quick deal on the rights of expat citizens after Brexit has received a cool reception from EU grandees as Britain’s withdrawal was pushed to the margins of the two-day Brussels summit.

Donald Tusk, President of the European Council of EU leaders, dismissed the Prime Minister’s “fair and serious offer,” saying it fell below expectations and could worsen the situation of the 3.2 million EU citizens living in the UK.

His colleague, Jean-Claude Juncker, President of the European Commission, said it was “not sufficient" while Angela Merkel, the German Chancellor, stressed how the UK Government’s proposals did not represent a "breakthrough" in the Brexit talks.

At home, Mrs May was attacked by her onetime cabinet colleague, George Osborne, the former Chancellor, whose editorial in the London Evening Standard denounced the PM’s offer as an “act of self-interest dressed up as a gesture of international generosity".

He accused her of blocking David Cameron's preferred unilateral option on EU citizens’ rights when she was home secretary.

At a press conference in the Belgian capital, Mrs May was confronted with Mr Osborne’s claim and refused to give an outright denial, saying: "That's certainly not my recollection."

Under the UK proposals, which the PM outlined to her fellow leaders over dinner on Thursday, all EU nationals who have been in the UK for five years would be entitled to "settled status," granting them the same rights as their British neighbours to healthcare, education, welfare benefits and pensions.

Those with a shorter period of residency would be able to stay on to reach the five-year threshold and others arriving after a yet-to-be-defined cut-off date would have a "grace period" to regularise their status.

Mrs May said her offer gave “those three million EU citizens in the UK certainty about the future of their lives and we want the same certainty for the more than one million UK citizens who are living in the European Union".

But the 3 Million group, which represents EU nationals in the UK, branded it “slightly pathetic,” saying the UK offer failed to end uncertainty over the reunification of families, the right to work, the recognition of professional qualifications and the ability to retain UK rights when moving between and working across different European countries.

The two-day summit ended with battle-lines being drawn over the key questions of jurisdiction and the cut-off date for residency rights.

Mr Juncker argued that it was "inconceivable" that the European Court of Justice would have no judicial role in enforcing EU nationals' rights under any future arrangements.

But Mrs May set her face firmly against the European court’s involvement while suggesting expats' rights could be protected by international treaty.

"They will be enshrined in UK law, they will be enforced through the highly respected UK courts, and, of course, if this is an aspect of the withdrawal treaty, then it will be enshrined in international law as well," she said.

The PM insisted several leaders, including Poland's Beate Szydlo, had "reacted positively" to her proposals.

Mr Tusk made clear that the UK offer would be subjected to line-by-line analysis by the Brexit negotiation team led by Michel Barnier following its publication on Monday.

But he added: "My first impression is that the UK offer is below our expectations and risks worsening the situation of citizens."

A formal proposal tabled by the EU would guarantee lifetime protection for those arriving in the UK all the way up to the date of Brexit, expected in March 2019, and would require Commission monitoring and ECJ enforcement of their rights.

Speaking alongside France’s Emmanuel Macron in a rare joint press conference which was a mark of both sides' determination to show Paris and Berlin driving the EU, Mrs Merkel described the May plan as a "good beginning" but added that there was "a long way to go yet".

"That was a good beginning but - and I'm trying to word this very carefully - it was not a breakthrough," she said; to agreement from the French President.