By Chris Mason
Europe correspondent, BBC News
There is an average of 253 people in every square kilometre of the UK
Immigration levels have pushed population density in England to a higher level than any other major country in Europe.
The figures, released by the Office for National Statistics, indicate there is an average of 395 people in every square kilometre in England.
This is an increase of five per sq km in the past two years.
The increase has pushed England's population density above the previous highest figure set by the Netherlands.
Within the European Union, only the island of Malta has a higher population density than England.
Its population, though, is just 400,000.
The statistics have been released in response to a parliamentary question from the Conservative MP for Hertsmere in Hertfordshire, James Clappison.
He asked the government how crowded the UK is and how it compared with countries around the continent.
The latest projections suggest there is an average of 253 people in every square kilometre of the UK.
But Scotland, Wales and Northern Ireland are relatively sparsely populated.
The figure for England alone puts the country top of the European league for the most crowded major countries - and density is expected to rise to 464 people for every square kilometre by 2031.
Much of the recent immigration from Eastern Europe has been concentrated in the South and East, which has seen high demand for labour in farming and construction.
But there are growing concerns the increases are not sustainable.
"This worries people - and it worries people with good reason," Mr Clappison, an MP in the South East, said.
"Population density has direct implications for quality of life - it adds pressure on public services, it adds pressure on infrastructure and it adds pressure on the environment."
Last week an all-party group led by former Labour minister Frank Field and Conservative MP Nicholas Soames called for a "balanced" approach to immigration, where the numbers allowed to settle in the country equalled those leaving.
Sir Andrew Green, the chairman of Migration Watch UK, echoed that suggestion.
"These figures are a milestone and a wake up call," he said.
"We simply can't go on as we are. The government's own forecasts show that England alone will add nearly 10 million to its population in the next 25 years and 70% of that is down to immigration.
"That's the equivalent to seven times the city of Birmingham in the next quarter of a century. Clearly that's not acceptable."
But some argue that immigration levels are likely to ease as the UK's economy falters and there are fewer jobs available.
And the government, for its part, is hoping its new so-called "points based" migration system will make a difference.
A spokesman for UK Border Agency told the BBC: "Our tough new points system plus our plans for newcomers to earn their citizenship will reduce overall numbers of economic migrants coming to Britain, and the numbers awarded permanent settlement.
"Crucially the points system means only the migrants with the skills Britain needs can come - and no more."
But critics have argued that without an annual cap on the number of immigrants entering the UK, a points based system is pointless.