There “may be” a million illegal immigrants in Britain, the Home Secretary has admitted.

Amber Rudd confessed she simply didn’t know how many people are in the UK against the law.

The Tory Cabinet minister was quizzed over claims by David Wood, a former head of immigration enforcement, that there are “probably over a million foreigners here illegally” and “no one could ever remove them really.”

Asked if his estimate of a million was a “sensible judgement”, Ms Rudd said: “It may be.

“But we need to deal in facts, and there aren’t facts to back that up, unless he gave you some which we don’t know about.”

Asked to confirm she could not dispute the figure, because she did not know, Ms Rudd replied: “I think that’s correct, yes.”

Tory MP Christopher Chope fumed: “So he may well be right.”

Ms Rudd shot back: “Or wrong!”

Home Office Permanent Secretary Philip Rutnam added: “It’s not something we have an estimate of.”

Ms Rudd insisted there was “very little overstaying” by students and emphasised enforcement action during the clash with the Commons Home Affairs Committee.

But Mr Chope complained the target of removing 35,000 people from Britain was a “drop in the ocean”.

He claimed: “Why is it the government’s view that TV licence evasion is more serious and needs more deterrents than illegal migration?”

Amber Rudd was quizzed by MPs

Ms Rudd rejected the claim, replying: “If we have illegal migrants, what we want to do is remove them - they are here illegally.”

She added she did not recognise figures of 150,000 to 200,000 foreign nationals failing to return.

In an earlier angry clash, Ms Rudd admitted not one of 280 empty spaces for refugee children in Britain has been filled.

She blamed Greece and Italy for the hold-up with the placements - and couldn’t guarantee they will be by Christmas.

Furious Home Affairs Committee chair Yvette Cooper said the slow progress was “hopelessly bureaucratic”, “unconvincing” and ran “against the spirit” of the law.

Yvette Cooper chair of the home affairs select committee

She added: “Frankly there are 63,000 unaccompanied minors in Europe.

“Surely it shouldn’t be beyond the wit of the Home Office to find a way to fill 280 places!”

The places were offered by councils under the so-called Dubs amendment, which committed to bringing unaccompanied refugee children from Europe to the UK.

The policy was a special exception to Britain’s policy of refusing refugees who are already inside the EU unless they already have family here.

Ms Rudd said: “I believe it is right we help the most vulnerable children.

“We have sent ministers over, we have sent officials over, we are committed to filling them.”

Amber Rudd said she was “horrified, upset and disgusted” by BBC Panorama’s revelations of abuse at the Brook House immigration removal centre near Gatwick.

But she said private operator G4S “seem committed” to making changes.