More than a million illegal immigrants living in Britain unlawfully are unlikely ever to be removed, MPs have been told.

Ex-director of immigration enforcement David Wood told the Commons home affairs committee there are “enormous difficulties” in removing illegal immigrants, and that the majority of foreigners living ‘under the radar’ in Britain are set to stay.

He said: “There are probably over a million foreigners here illegally at the moment. There’s a large number, so no one could ever remove them really.

“But what there needs to be is a consequence, there needs to be seen that there is a risk that if you don’t abide by the immigration rules, and you overstay or you commit crimes, there is a consequence and a real risk of being removed.”

An official said there were too few staff for the number of migrants https://t.co/kf1R2ezmUa — Breitbart London (@BreitbartLondon) February 20, 2017

Wood, who retired from his Home Office post in 2015, made the assessment Tuesday when giving evidence to the home affairs committee, which is looking at the immigration system’s capacity to cope with possible challenges posed by Britain’s withdrawal from the European Union (EU).

“Right across the immigration system, I don’t think it was ever greatly well resourced and it’s becoming tighter and tighter,” he said: adding: “I don’t think under current resources that the challenge of Brexit can be met, and certainly not met smoothly.”

Noting that the UK’s exit from the bloc could result in a “whole group of potential illegal immigrants that there wasn’t before,” Wood warned pressure on resources could see Europeans become “easy candidates for removal” while “more harm based cases” of foreign nationals staying unlawfully will be left alone.

“That is a bit of a worry going forward,” he said, speaking of how a post-Brexit migration system will create a new illegal immigrant category of EU nationals who overstay their visas.

UK Judge: ‘Country Can’t Cope’ More Than 1 Million Illegals May Be In London Alone https://t.co/IsqNvlkqHC pic.twitter.com/oKdlKnNaIH — Breitbart London (@BreitbartLondon) August 22, 2016

The government has kept secret its estimates of illegal immigrant numbers since 2005, but in a paper for Civitas published in June, co-written with former Home Office speechwriter Alasdair Palmer, Wood revealed the department estimates that, annually, up to 250,000 foreign nationals who are supposed to return to their home countries fail to do so.

In addition to visa overstayers — a category which includes students and others — the figure includes bogus asylum seekers, of which there were around 26,000 last year, and migrants who break into Britain riding in the back of trucks.

In April, Breitbart London reported that deportations of failed asylum seekers was at a record low, with the number successfully removed from the UK having fallen by two-thirds since the Conservatives came to power in 2010, despite the party’s tough talk on immigration.