The key measure of immigration to the UK has reached a new record high as soaring numbers of people flock to the country for work.
Estimated net migration was 336,000 in the year to June - a jump of 82,000, or a third, compared with the previous 12 months, according to the Office for National Statistics (ONS).
The surge in arrivals is being driven by a record influx of people arriving for jobs, while a dramatic rise in the numbers of Romanians and Bulgarians coming to Britain was also revealed in the data.
Net migration - the difference between the number of people arriving and leaving - has now been at an unprecedented level for two consecutive quarters.
It is 16,000 higher than the previous peak recorded in the year ending June 2005, when enlargement of the European Union saw a surge in arrivals.
The findings sparked fresh questions about the Government's aim of reducing net migration to below 100,000.
Experts reported immigration was at 636,000 - a "statistically significant" increase of 62,000 on the same period last year - while emigration fell 20,000 to 300,000.
Jay Lindop, head of population statistics at ONS, said: "Today's figures show that annual net migration is at a similar level to that reported last quarter and remains the highest on record."
The data showed that:
:: Romania is now in the top five of countries where those coming to Britain previously lived for the first time and estimates of the number of Romanian immigrants have increased by 127% compared with 2013.
:: A total of 50,000 Romanians and Bulgarians came to the UK in the year to June, a rise of 19,000 - or 61% - compared with the previous year. Restrictions on citizens from the countries working in Britain were lifted in January 2014.
:: Net migration of European Union (EU) citizens has increased 42,000 to 180,000, with the non-EU level up by 36,000 to 201,000.
:: A total of 294,000 people came to the UK for work in the year to June, with nearly two in three (64%) having a definite job to come to.
:: Three quarters of the growth in employment over the last year was accounted for by foreign nationals.
:: The number of people from overseas registering for national insurance numbers - needed to take up employment - jumped by almost a third (29%) to 862,000.
The latest data prompted scrutiny of the Government's record on the issue and the renegotiation of EU membership.
Alp Mehmet, vice chairman of campaign group Migration Watch UK, said: "These are very disappointing figures - net migration is running at a third of a million a year with no sign of any forthcoming reduction.
"If these numbers continue the pressure on our infrastructure will intensify. For example, the efforts announced yesterday to increase house building will be wholly inadequate in addressing the huge demand on housing."
Robert Oxley, of Vote Leave, said:"While the UK remains a member of the European Union, we cannot control our borders."
A number of measures to reduce net migration have been implemented in recent years and a bill currently going through Parliament includes new sanctions for illegal workers.
Madeleine Sumption, director of the Migration Observatory at the University of Oxford, said: "At this point, changes in net migration are mainly being driven by economic factors like the success of the UK economy rather than by new policies."
Immigration Minister James Brokenshire admitted the figures "underline the challenge we face to reduce net migration to sustainable levels".
He said: "We remain committed to reforms across the whole of government to deliver the controlled migration system which is in the best interests of our country."
Student fraud has been slashed and access to welfare toughened, he claimed, but conceded there is "much more to do".
Mr Brokenshire said the new bill will address "pull factors" that draw migrants to Britain, adding that record levels of EU immigration "show why the PM is right to negotiate with the EU to reform welfare to reduce the financial incentives that attract EU migrants to the UK".