Foreign immigrants are arriving in Britain at the rate of one every minute
At the same time the number of UK citizens emigrating to live abroad equates to one every five minutes.
The figures emerged less than a week before Romania and Bulgaria are due join the European Union on January 1 - giving 30 million more people the right to enter and work in Britain.
The latest EU expansion is expected to unleash another huge wave of immigration similar to that seen in 2004 when eight former communist states joined the Union.
The analysis of official Government immigration statistics by the MigrationWatch think tank found that 1,500 foreigners arrived in Britain each day in 2005, intending to settle for at least a year - just over one for every minute of the day.
Today's report claims those figures are probably a dramatic under-estimate, as counting methods focus on three main airports, largely ignoring coach services and budget flights to regional airports favoured by eastern Europeans.
Officially only 65,000 eastern Europeans were classified as immigrants but the study suggests the real figure could be twice as high.
The net outflow of British citizens leaving to live abroad rose to 107,000 last year - equivalent to one Briton quitting the country every five minutes, or almost 300 per day.
The UK also experienced a net inflow of 800 foreign immigrants each day - the total of newcomers arriving to settle here, minus the number of foreigners leaving Britain after living here for a period.
Taken together those figures provide a striking illustration of the pace of change imposed on British society by population movements, with net immigration trebling in scale over the past ten years.
Despite the focus on the numbers of immigrants arriving from eastern Europe in recent years, the MigrationWatch study shows that this inflow accounts for only a fifth of total immigration, most of which comes from Africa and Asia.
The largest group of migrants were people from India, Pakistan, Bangladesh and Sri Lanka, who accounted for two-thirds of net immigration.
According to the Office for National Statistics Britain's population rose by 500 people per day last year, or 185,000 over the year.
That figure is slightly down on the previous year's figure of more than 220,000, but was still the second highest in Britain's history.
MigrationWatch called for tougher measures to reduce immigration from outside the EU to 'manageable and realistic levels', and to impose tougher controls on countries hoping to join the EU in future.
Four in five immigrants are from Africa and Asia
'One immigrant a minute enters UK'