Romanians and Bulgarians will be allowed free entry into the UK from Wednesday.
But a hush-hush study says the impact could be devastating.
No-one knows how many migrants will arrive, but the report says it could be far more than the 50,000 forecast.
It
predicts tension between the new migrants and those already living here
if they undercut the wages of Polish workers as well as Brits.
Serious conflicts could flare in what is described as a breakdown in “social cohesion”.
Former Labour Home Secretary David Blunkett, 66, has predicted an “explosion” in his home
city of Sheffield if the local Roma community do not do more to fit in.
The report was commissioned by the Home Office and produced by academics from Reading University.
It also warns of massive pressure on schools, hospitals and the benefits system
Igor Kaminski, who runs a Polish building firm in London, said:
“There’s a lot of fear the cheaper end of the market will collapse under
pressure from Bulgarians and Romanian workers who, for a short time,
will accept any prices.”Tory MP Dr Sarah Wollaston said: “Our population is already rising faster than any other country in Europe, with one third the result of immigration. The pressures on infrastructure and employment can no longer be ignored.
“It is also right that Prime Minister David Cameron should concern himself with deteriorating community relations in places like Sheffield, and right that he considers the consequences of doing nothing. He must grasp the nettle.”
An ICM poll yesterday found that 72% of Brits think restrictions on Romanian and Bulgarian migrants should be kept in place.
And another survey by Ipsos MORI found two thirds of people would only welcome newcomers if they work, pay taxes and learn English.
Among those planning to come is jobless Romanian Toni Samdu, 40, wife Mia, 38, their four children, aged six to 14, and gran Elena Moise, 64, who live in poverty in Barbulesti.