The British government is breaching the withdrawal agreement with the European Union by requiring EU citizens to reapply for the right to live and work in the United Kingdom, an independent body set up to oversee citizens’ rights told a London court on Tuesday.

The Independent Monitoring Authority (IMA) says the Home Office’s post-Brexit settlement scheme unlawfully requires up to 2.6 million EU citizens to make a second application after being allowed to remain in the UK or lose their rights of residence.

EU citizens and their family members who had not established a right of permanent residence before the end of 2020 can be granted limited leave to enter and remain in the UK for five years, known as “pre-settled status”.

Robert Palmer, representing the IMA, told London’s High Court that those who do not make another application within five years of being granted pre-settled status will “automatically lose their right to residence in the UK, making them an illegal overstayer who is liable to detention and removal”.

He said that this aspect of the EU settlement scheme – and a similar scheme for citizens from the countries of the European Economic Area and the European Free Trade Association – is “straightforwardly incompatible with the withdrawal agreement”.

Palmer also said the European Commission, which has intervened in the case, supports the IMA’s interpretation of EU citizens’ rights under the withdrawal agreement.

David Blundell, representing the Home Office, argued in court documents that the settlement scheme gives EU citizens “significantly more generous protection” than is required under the withdrawal agreement.

He also said that the British government had “consistently adopted a position that an application would be required to renew pre-settled status” in its negotiations with the European Commission (EC).

Nicholas Khan, representing the EC, told Judge Peter Lane that the commission has intervened in the case because of “the importance of the matter to the proper functioning of the withdrawal agreement”.