The UK faces political disintegration in the face of "unprecedented" levels of immigration, a report has said.
Today's study from think-tank Civitas dismisses claims that mass immigration to the British Isles is nothing new and that the UK is a "mongrel nation already".
Its author David Conway, emeritus professor at Middlesex University, also opposes the Commission of Racial Equality's view that "everyone who lives in Britain today is either an immigrant or the descendant of an immigrant".
In his report, Professor Conway says that Britain's "cohesion" as a nation is under threat.
"The country may possibly have already reached a tipping point beyond which it can no longer be said to contain a single nation," he writes.
"Should that point have been reached, then ironically, in the course of Britain having become a nation of immigrants, it would have ceased to be a nation. Once such a point is reached, political disintegration may be predicted to be not long in following."
Last year the Home Office revealed that 600,000 workers from newly-acceded EU states had come to the UK, but the department insisted that the economic migrants, mostly from Poland, were "making few demands on our welfare system".
Professor Conway accuses the government of signalling "unending mass immigration" by abandoning the goal of limiting new workers arriving from other shores.
His report claims that immigrants are now adding one per cent to Britain's population every two years, with annual immigration applications to the UK increasing 20-fold since the 1980s.
Commenting, shadow home secretary David Davis said that Prof Conway's study had underlined the government's "inability to get a grip on immigration".
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