Politicians must take care not to demonise immigration as a "deep menace" to society, the Archbishop of Canterbury warned after a Cabinet minister suggested some parts of the country felt "swamped" and "under siege" from foreign arrivals.

The Most Rev Justin Welby said he was worried about the use of language in the debate amid an upsurge of abuse and urged people not to suggest new arrivals could "overwhelm" Britain.

Defence Secretary Michael Fallon has admitted he was "a bit careless" with how he phrased his concerns in a weekend television interview, but maintained that the "large number" of immigrants coming from the continent was putting pressure on housing and essential services in the UK.

Under pressure from Ukip and with a crunch by-election looming in the Rochester and Strood constituency, Mr Fallon had significantly ramped up Tory rhetoric on the sensitive issue.

Action was needed, he declared, "to prevent whole towns and communities being swamped by huge numbers of migrant workers".

A Government source said the Defence Secretary should have "chosen his words better" as Downing Street sought to calm the situation.

The Archbishop - who said he was not criticising any individual - appealed for moderation.

"Do I worry about the language? Yes I do, I really do," he told journalists at a Westminster lunch.

"We can't overburden communities, we have to be realistic about that.

"But at the heart of Christian teaching about the human being is that all human beings are of absolutely equal and infinite value and the language we use must reflect the value of the human being and not treat immigration as a deep menace that is somehow going to overwhelm a country that has coped with many waves of immigration and has usually done so with enormous success.

"It is part of the strength and brilliance of this country that we are so good at this, and I would hate to see us lose that."

Pointing to his own roots as the grandson of a German Jew, he said: "Every wave of immigration has been controversial when it comes.

"The British are a very mixed bunch. There are very few of us who trace ourselves back to the pre-Romans which was an unfortunate wave of immigration."

He went on: "With some people we have a duty of care. We also have a duty of care to the poorest of our own land and to managing the process of immigration prudently and carefully, but also generously and hospitably."

"We have 9,000 clergy working in 16,000 parishes, living in these parishes. We have better reports from the grassroots than almost anyone.

"What we are seeing is an upsurge of minor racist, anti-Semitic, anti-Islamic, anti-foreigner xenophobic - not major things, just comments being made, things being said which are for the people who grew up in those backgrounds seriously uncomfortable, really quite frightening.

Standing by the substance of his remarks, Mr Fallon told Sky News: "I was a bit careless with my words, I accept that.

"But, yes, there is pressure now, there are a large number of people coming here from the rest of Europe - this is one of the more successful economies in Europe and there is pressure as a result of that migration on social services, on housing, on school places for example.

"That's what the Prime Minister will be addressing when he puts forward his proposals for some kind of control."

Labour's Keith Vaz, chairman of the influential Commons Home Affairs Select Committee, said Mr Fallon's original comments had been "nasty, inappropriate and wrong".

The Prime Minister's official spokesman said: "It is right to take care in the language that is used."