The British government’s plan to force EU nationals to register as part of a transition deal would be illegal, the Home Secretary has been warned.

A group of MEPs from across Europe have written to Amber Rudd after she suggested the idea, which was also floated in Theresa May’s Florence speech, in front of a parliamentary committee.

Though some European Union countries such as Belgium force migrants to register, this is as part of a national identity scheme that requires all residents to register.

“Is the Home Office suggesting that only non-UK EU citizens needs to register? Article 26 of the freedom of movement directive makes it very clear that residency cards are for everyone, or no one,” the MEPs said in a letter first published by the Guardian newspaper.

“We find it extremely troubling for the home secretary of a member state currently complying with EU laws to make such a statement.”

The MEPs in question are Sophie in ’t Veld, Seb Dance, Jean Lambert, Claude Moraes, Beatriz Becerra, Cecilia Wikström and Catherine Bearder.

Under the proposed transition period as envisage by the Prime Minister the UK would comply with EU law.

The proposed registration system would be the starting point for a post-Brexit immigration system, under the proposals.

The European Parliament has a final veto on any Brexit deal, though day-to-day negotiations are conducted by the European Commission under the auspices of a mandate set by the Council.

The EU has so far refused to discuss any transition period until separation issues have been dealt with sufficiently – the Northern Ireland border, EU citizens’ rights, and the divorce bill.

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During her Florence speech, Ms May said: “During the implementation period, people will continue to be able to come and live and work in the UK; but there will be a registration system – an essential preparation for the new regime.”

EU citizens coming to the Britain do not currently require any special documentation to come and live and work in the UK.