Three million European Union citizens in Britain could have to be deported in event of a ‘Brexit’ a Home Office minister has suggested, a claim that was denounced as "absurd" by anti-EU campaigners.

The Government was branded “deeply irresponsible” by anti-EU campaigners for trying to “whip up a climate of fear”.

Ministers were asked in the House of Lords “whether it is their intention that, in the event of the UK leaving the EU, citizens of EU member states who had previously settled in the UK would be entitled automatically to remain”.

In reply, Lord Keen of Elie, a Government minister, said: “As set out in the Government’s White Paper: ‘The process for withdrawing from the European Union’, published on 29 February, the withdrawal process is unprecedented.

“No country has ever used Article 50 – it is untested. There is a great deal of uncertainty about how it would work.

“UK citizens get the right to live and work in the other 27 member states from our membership of the EU.

“If the UK voted to leave the EU, the Government would do all it could to secure a positive outcome for the country, but there would be no requirement under EU law for these rights to be maintained.”