THERESA May has admitted she cannot guarantee the status of an estimated 1.2 million UK nationals living in other EU countries if Britain fails to reach a withdrawal deal with Brussels.

And she warned that rights held by more than three million EU nationals in the UK could “fall away” if the hoped-for agreement is not sealed by the date of Brexit in March 2019.

Answering questions from callers on an LBC radio phone-in, Mrs May was challenged by a woman from north London called Nina, who has been in the UK for 30 years, over whether the PM could guarantee her right to stay following Brexit.

Mrs May said she wanted people like Nina to be able to remain and was seeking agreement with the remaining 27 EU states on reciprocal rights for Britons living on the continent.

But she said: “The point is that there are certain rights that pertain to somebody who is an EU citizen here in the UK by virtue of being an EU citizen - things like benefits they are able to access in relation to their home country and in relation to the UK.

“Some of those issues would fall away if there was no deal because there wouldn’t be agreement between us and the EU about how those things would be looked at, so we would have to look at these issues separately in a no deal scenario.”

And on the status of British nationals in Europe if no deal is reached, Mrs May said: “We don’t know what would happen to them. The EU member states would have to consider what their approach would be to those UK citizens.

“By definition, if there isn’t a deal we won’t have been able to agree with the EU what happens to UK citizens currently living in countries like Spain and Italy and other members of the EU.”

Mrs May made clear on Monday that the Government is making active preparations for a “no deal” scenario, publishing policy papers setting out how Britain would deal with trade and customs arrangements if no agreement is reached.

But European Council president Donald Tusk said that Brussels was making no plans for what would happen if talks fail and Britain crashes out without a deal.