Work on a separate registration scheme for European Union (EU) migrants arriving after Brexit has “barely begun” and “almost certainly” will not be ready in time, government sources have said.

The Prime Minister has claimed that EU migrants arriving after the divorce date will not be afforded the same rights to stay permanently and bring family over as the millions already here, and a registration system is needed to ensure this promise can be implemented.

Jacob Rees-Mogg, the Tory MP for North East Somerset and chairman of the European Research Group, told The Times that Whitehall’s “incompetence” would be displayed if the system were not ready.

“If this were true it would be a sad admission of incompetence at the Home Office and it would be hard to believe that someone as efficient as Amber Rudd would accept such a sorry state of affairs,” he blasted.

The government and immigration officials need to implement the new system for the transition period, as well as devise a system to be implemented following the transition period, which is yet to be agreed.

However, two senior government sources said that preparations had “barely begun” and there was widespread concern that it cannot be delivered in time.

“Rightly the focus has been on registering the three million nationals who are already here, and while that has been progressing well there is still a lot of work to do,” one told The Times.

“But the problem is that this is a streamlined process that doesn’t question whether in future someone might not have the right to work.

“That work has barely begun and I don’t think anyone has any confidence that a such a new system can be ready for March next year.”

Another corroborated the claim and said the concerns about the lack of progress have been raised with the Brexit department.

“The way things look at the moment it almost certainly won’t be ready. The government doesn’t have the best record of these kind of projects anyway and the most pressing priority is to ensure that nothing goes wrong with registering existing EU nationals. If that goes wrong it will be a disaster.”

A Home Office spokesman said: “The prime minister has been clear that during the implementation period there will be a registration system for EU citizens coming to the UK.

“The precise details of the implementation period are currently being negotiated with the EU, but planning is well underway.”