UK Home Office minister Brandon Lewis | Dan Kitwood/Getty Images UK minister: EU nationals without settled status could be deported Home Office Minister Brandon Lewis says ‘existing immigration rules’ would be applied to EU citizens without settled status.

The U.K. may deport EU citizens who have not registered in its settlement scheme by the end of next year, a government minister said Thursday.

Home Office Minister Brandon Lewis told German newspaper Die Welt that EU nationals who have not applied to formalize their status will be subject to “the existing immigration rules.”

Asked in an interview whether they could face deportation, Lewis said: “Theoretically, yes.”

The government launched its settlement scheme at the end of March to register EU citizens already resident in the U.K. and formalize their right to work and access public services. All EU nationals who arrive in the U.K. before Brexit day are eligible to apply and must do so by December 31, 2020 if the U.K. leaves the EU without a deal or by June 30, 2021 if there's a deal.

“If EU citizens have not registered by this point in time and do not have an appropriate justification for that, the current immigration rules will be applied,” Lewis told Die Welt. He added that the settled status process had been launched to prevent EU citizens from “getting caught up in such a situation.”

EU nationals who have not applied to formalize their status will be subject to “the existing immigration rules," Brandon Lewis said.

This is the first time the U.K. government has set out its intended consequences for EU nationals who do not secure settled status.

However, the government must pass new legislation if it is to introduce immigration restrictions for EU nationals. Freedom of movement would not automatically end if the U.K. leaves the EU without a deal because EU law will continue to apply until its foundation is repealed.

Approximately 1.5 million of the roughly 3.6 million Europeans living in the U.K. have secured settled status through the scheme, according to the latest figures released by British government earlier this week.

The3million group, which represents EU citizens living in the U.K., said: “It is not too late to stop this madness of turning law abiding citizens into unlawful residents. The status can still be made automatic, put into law now, and for the EU Settlement Scheme to be changed from application to registration.”

Liberal Democrat Shadow Home Secretary Christine Jardine said: “I am absolutely appalled. Brandon Lewis has finally confirmed what we’ve known all along: Boris Johnson has no intention of keeping his promise to automatically guarantee the rights of EU citizens living in the U.K. "

"EU citizens are our friends, family and neighbors and we want them to stay," a Home Office spokesperson said in a statement. "The EU Settlement Scheme is a free and easy way for EU citizens to get the U.K. immigration status they need. We’ve always been clear that where they have reasonable grounds for missing the deadline, they’ll be given a further opportunity to apply."

Cristina Gallardo contributed reporting.