EXPERTS attacked an anti-EU migration observatory for making “sweeping” predictions yesterday after it claimed that 250,000 people a year would move to Britain over the next 20 years.

According to a report by Migration Watch, if Britain votes to remain in the European Union, “very high levels of net migration” and “widespread complacency and denial about both the likelihood and the impact of rapid population growth” would continue.

But the claims were challenged by the Joint Council for the Welfare of Immigrants (JCWI), which argued that migration was necessary for the recovery of the British economy.

And while Migration Watch asserted that a wave of people equal to “roughly the population of Southampton” would come to Britain from the EU every year, JCWI pointed out that non-EU migration was actually higher.

JCWI chief executive Saira Grant said: “Migration Watch accepts that, in the short term, only economic failure will reduce immigration into the UK.

“Another recession is a high price to pay for a drop in demand for workers and would hit those on the lowest pay hardest.

“Leaving aside the inherent problems with making such sweeping long-term predictions about migration trends, this report fails to take into account the essential contributions that migrants make to the UK.

“The real questions that this report raises for politicians are about why we have failed to reinvest the economic benefits of migration in our local communities, schools and basic infrastructure.

“Decades of underinvestment in basic public services have left many communities feeling the strain, and yet it seems that it is far easier to blame migrants, who are helping to keep the system running, rather than addressing the root causes of these problems.”