The number of foreign-born people in Britain has topped the eight million mark for the first time, according to new statistics by The Migration Observatory at Oxford University.
Official figures due to be released on Thursday are likely to show the landmark was reached last year.
The news comes as ministers are bracing for further statistics set to be unveiled on Thursday which will show that net migration has once again increased.
Previous data showed that in 2013 there were 7.9 million people living in the UK who were born overseas.
Madeleine Sumption, director of The Migration Observatory, said: “Given that we know net migration has been running in the hundreds of thousands since 2013, it would be surprising if the foreign-born population didn’t go above eight million.
“The numbers have gone up steadily over time.”
Immigration figures will also be published alongside the population data.
They could show the key measure of net migration – the difference between the number of people entering minus the number leaving – has reached a record level.
It will mean that Prime Minister David Cameron’s plan to bring the figure down to under 100,000 comes under intense scrutiny.
Previous statistics showed that 2.7m of the foreign-born population were born in EU countries, while 5.2m were from nations outside the bloc.
The total of 7.9 million indicated that one in eight people living in the UK was born abroad and was a jump of 50.7% compared to nine years earlier.
However, the rate of increase in the foreign-born population has slowed in recent years – rising by 5.9% in 2011, 2.1% in 2012 and 1.3% in 2013.
Ms Sumption said that since 2004, EU migration has increased by more than non EU migration in percentage terms.
“Traditionally most immigration to the UK has been of non-EU citizens,” she said.
“It remains the case that non-EU citizens make up a substantial share of the total, but recently the share of EU migration has approached about half of all non British migration, which is unusual by recent historical standards.”
The strength of the British economy and expansion of the European Union have been cited as key factors for the continued increase of migration not only from Eastern Europe but Western Europe as well.
As a result, the Government has continued to crack down on migration from outside the European Union.
International Student numbers from South Asia for instance, have seen a dramatic decline.
The Government has also announced new measures which will be included in the Immigration Bill this autumn, including jail terms for illegal immigrants and temporary closure of businesses found employing them.
Details of the legislation were revealed after the Government faced criticism for its handling of the Calais crisis and days before the release of the latest immigration figures.
The last set of data showed that net long-term migration – the number of people entering the country minus the number leaving – was 318,000 in 2014.
Only a small increase would be needed in the new statistics to surpass the highest figure on record, which was 320,000 in the year to June 2005.
Alp Mehmet, of Migration Watch UK, said: “This very rapid increase in our population is the direct consequence of Labour’s mass immigration which the coalition were unable to bring under control.
“The Government must now get a grip of the student route which is the major avenue for non-EU migration. They must also renegotiate access to Britain by EU migrants, particularly those coming for low wage employment.”
“What is certain is that far more resources are needed to get immigration back under control.”