Theresa May's offer on residency rights for EU citizens following Brexit is "a first step, but this step is not sufficient", the president of the European Commission has said.
Jean-Claude Juncker's comment came shortly after the Prime Minister accepted the terms she set out for EU nationals remaining in the UK will be challenged by Brussels.
Under the proposals, which Mrs May outlined to fellow leaders at a EU summit on Thursday, the settled status will be available to all EU nationals who have been in the UK for five years, granting them the same rights as British citizens to healthcare, education, welfare benefits and pensions.
Mrs May's "fair and serious" offers is likely to be contested over jurisdiction and the cut-off date for eligibility and were depended on the EU offering a reciprocal offer to British migrants.
Her proposal was dismissed as "pathetic" by a group campaigning for an estimated three million European expats living in the UK.
Arriving for the second day of the summit on the anniversary of the referendum on June 23 last year, which paved the way for Brexit, Mrs May said EU expats should take "reassurance and confidence" from the package.
"I want to reassure all those EU citizens who are in the UK, who have made their lives and homes in the UK, that no one will have to leave. We won't be seeing families split apart," she said.
"This is a fair and serious offer. I want to give those EU citizens in the UK certainty about the future of their lives, but I also want to see that certainty given to citizens who are living in the EU."
But the co-chairman of the 3Million movement, Nicolas Hatton, retorted: "There is something slightly pathetic about the Prime Minister's proposal which makes no reference to the detailed, comprehensive offer tabled by the EU. The Prime Minister described her proposal as fair and serious. It's neither fair nor serious."