Worried EU nationals have been told not to apply to stay permanently in the UK – after the Home Office was deluged with applications.

Officials are instead advising EU citizens who fear for their future after Brexit to “sign up for email news alerts” about what action they may need to take in the future.

The stance was immediately attacked by the Liberal Democrats as evidence that “the nasty party are back”, with a warning the Conservatives would fail to give badly needed reassurance.

Experts pointed out that EU citizens had no choice but to apply for residence if they wanted to bid to become British citizens.

Furthermore, the Home Office stance directly contradicts the advice of EU embassies, such as Poland’s, which is for its citizens to apply for residence, to remove uncertainty.

Theresa May has refused to grant the 3 million EU nationals in the UK the right to remain and work after Brexit until the 1.1 million British expats in the EU are given the same guarantee.

She also heightened their fears by insisting she was happy to walk away from the EU with “no deal” if necessary – which would include no agreement over expats’ rights.

As a result, residency applications from EU citizens have mushroomed from less than 10,000 in the summer of 2015 to around 45,000 in the same three-month period a year later.

Colin Yeo, a barrister specialising in UK immigration law, said: “It is utterly unrealistic for the UK Government to now expect EU citizens to simply sit on their hands and trust the UK government to do the right thing.”

And Tom Brake, the Lib Dem foreign affairs spokesman, said: “If this is meant to reassure EU citizens who have made Britain their home then it has completely failed.”

The new Home Office guidance appears to be an attempt to head off an expected avalanche of applications if the Brexit negotiations turn sour.

The European Parliament President has suggested the UK must accept that the European Court of Justice will rule over any agreement on EU citizens’ rights – which Ms May is unlikely to accept.

The guidance reads: “You do not need to do anything as a result of Article 50 being triggered.

“There will be no change to the rights and status of EU nationals living in the UK while the UK remains in the EU.

“Under EU law, you don’t need a document to confirm your residence status in the UK. If you’re planning to apply for a document just to confirm your status, you can sign up for email alerts instead.”

Those updates, the guidance added, would tell people “the steps that you may need to take to confirm your status in the UK after we leave the EU”.

The Home Office has been fiercely criticised for the huge bureaucracy involved in applying for permanent residence, including making the form a staggering 85 pages long.

Some EU nationals have been rejected on the basis that they did not take out comprehensive sickness insurance – when the requirement was barely known.