The number of people living in England and Wales who were born outside the UK has risen to 10 million, driven by a huge increase in Romanians, new census data has shown.
It means one in six people living in England and Wales was born abroad.
The international influx also shows London as a hot spot for immigrants, according to data released by the Office for National Statistics (ONS) on Wednesday.
The top five nationalities for non-UK residents are Indians, Poles, Pakistanis, Romanians and Irish.
ONS statistics show a 576 per cent increase in residents who were born in Romania — from 80,000 in 2011 to 539,000 in 2021.
Migration drove a 6.3 per cent rise in the population between 2011 and 2021, according to data from the most recent census, conducted last year.
The ONS said that 16.8 per cent of residents were born abroad, up from 13.4 per cent a decade earlier, and the number of usual residents who were born outside the UK had risen by 2.5 million since 2011.
The large increase in the number of those born in Romania followed the lifting of working restrictions across the European Union in 2014.
India was the most common country of birth outside the UK — with those 925,000 people making up 1.5 per cent of the population.
The data showed those who listed Ireland as their country of birth declined from 407,000 in 2011 to 325,000 in 2021.
“The census paints a picture of how the make-up of the population has changed in the past decade. That decade, of course, saw us leave the EU as well as live with the pandemic,” said census deputy director Jon Wroth-Smith.
“While these events may have had an impact on people's decisions or ability to migrate or travel at a given time, the census tells us about the change over the whole decade — who was living here in March 2021, compared with March 2011.
“We can see Romanians have been a big driver in this change, while there have also been increases due to migration from India, Pakistan and Poland, as well as southern European countries such as Italy.
“We can also see that migration in the year prior to census was lower in 2021 than it was in 2011.
“This is likely, in large part, due to the various travel restrictions in place during the coronavirus pandemic.”
Of the top 20 local authorities with the highest proportion of non-UK born residents, 18 were in London — the highest proportions being Brent, Westminster and Kensington and Chelsea.
Of the top 20 local authorities with the highest proportion of non-UK passport holders, 15 were in London, the top three being the City of London, Westminster and Newham.
The population of England and Wales for the 2021 census was found to be 59,597,300.
The figures are almost certain to fuel political debate over immigration policy.
While some in Prime Minister Rishi Sunak’s government want strict limits on the number of people coming to the UK, many others argue for a looser regime to boost the struggling economy and ease labour shortages in sectors such as hospitality.
There have also been record numbers of people entering Britain via English Channel trafficking routes to claim asylum.