The number of Romanians and Bulgarians working in the UK rose by a quarter in three months, new figures have shown.
The Office for National Statistics said 141,000 were employed from April to June compared with 112,000 in the previous three months - up nearly 26%.
This comes just before temporary restrictions on the type of jobs open to people from the two countries are due to expire later this year.
Here are five views on the impact that Romanian and Bulgarian immigration might have on the UK.
Nigel Farage, leader of UK Independence Party
So far the government has been in utter denial about the impact of opening the door in January to Romanian and Bulgarian immigration with no restrictions in the new year.
They have refused point blank to release their estimates about the numbers they expect to arrive and they appear to be engaging in a futile rejection of reality.
It is a simple fact that if you open your doors to people from countries with significantly lower wages and GDP than the UK then migratory flows will come.
In the main those arriving will be competing in the low-skills market and will put pressure on those sections of society least able to defend themselves.
My own experience of this is in taxi cabs where I am regularly booked into cabs driven by those who have been recruited as drivers in Bulgaria and Romania.
Nice enough people, but without any local knowledge. Even with a satnav to hand they invariably get lost.
In the meantime, British drivers are driven out of work as they, with mortgages and local ties, cannot compete on wages.
Of course, there is nothing that the government can do about the problem, as they are committed to membership of the EU, which is the root cause of the problem. To act, would be to break EU law.
Jonathan Portes, of National Institute of Economic and Social Research
The big picture is that most migrants from the new member states of the EU come here to work; they are young and place relatively few demands on public services.
Yesterday's figures showed migrants from Romania and Bulgaria are more likely to be in work than the population as a whole. However, the overall impact on the labour market is not likely to be that large - the increase in Bulgarian and Romanian workers in the latest statistics represents one in a thousand of the UK workforce.
Migrants in general, in particular those from the new member states, are less likely to claim benefits than the general population.
Future migration from Bulgaria and Romania is unlikely to have a significant impact on the NHS. Economic migrants, in particular, are generally young and healthy and do not make major demands on health services.
Any migration of families may potentially increase pressure on school places at primary level in areas experiencing pressure on places. While existing evidence suggests that migrant children do not have a negative impact on school performance, language assistance will need to be provided, at least for any new arrivals from Bulgaria and Romania.
Any impacts of migration on housing are most likely to be felt in the private rented sector.
Overall, our assessment is that the impacts on the UK economy and labour market are likely to be small, but broadly positive, as you would expect given that most new migrants will be relatively young and their primary motivation is to find work.
Max Wind-Cowie, of Demos
The impact of immigration on the economy, wages, resources and public services is much debated and hugely contentious. But at least there are numbers to work from.
Questions about the social consequences of an inflow such as that we have seen - and will see - of Romanian and Bulgarian migrants are even more complex.
Large and sudden arrivals can lead to extreme concentrations of migrant communities - people from Romania and Bulgaria, arriving en masse, will naturally congregate in places where there is unskilled, flexible work available and where friends and relatives may be already.
It is this accidental drift towards ghettoisation that has had such a profound impact on places like Boston. And when a new community effectively commandeers a place - including the public resources such as schools and hospitals that it offers - that leads to resentment and a steady erosion of our social fabric.
People become much less willing to pay into a communal pot when they think they can see it being exploited by people who do not appear to be making much of an effort to fit in with their new neighbours.
Pawel Swidlicki, research analyst at Open Europe
Free movement has been broadly beneficial for the UK but it needs to be delicately handled.
Although European migrants are distributed from low- to high-skilled jobs, migrants typically work in agriculture, catering, hospitality and construction.
It would be fair to say that the lowest paid are the most affected by immigration. In some areas such as Slough and Lincolnshire, there has been an increase in pressure on public services such as schools, the NHS and the police.
But there is no conclusive evidence that the last wave of immigration - when Poland, Hungary and others entered the EU in 2004 - had a negative effect on employment in the UK.
Employment among UK-born workers stayed roughly steady while overall job creation increased. In other words, EU migration didn't contribute to unemployment - but new jobs created often did not go to local workers.
Public confidence in migration is low. The perception is that it's too easy for EU migrants to access the social welfare system, even though employment is proportionally higher among migrants.
Part of the problem is the UK's "universalist" welfare system which makes it harder to monitor eligibility compared to the insurance-based models favoured on the Continent.
The public need to be reassured not only that people who have not paid into the system are not abusing it, but also that this cannot happen.
For this, there needs to be some mechanism by which the ineligibility of claimants can be determined, with rigorous testing and checks in place.
The EU ought to drop its counter-productive challenge against the UK's "right to reside" test and instead work with the UK and other member states to restore clarity to the overly complex rules governing EU migrants' access to benefits.
Sir Andrew Green, director of Migration Watch UK
The increase this year is a surprise given that the UK labour market is not open until next January.
And there's a wildcard in this. There are nearly a million Romanians living in Italy and another million in Spain, both of which have high unemployment, and so many may end up moving to Germany or the UK.
It is all pointing to a fairly significant movement of workers to the UK. We've estimated that there will be between 30,000 and 70,000 net migration from Romania and Bulgaria for each of the next five years.
In considering the impact on the UK, we should add this number to the present level of net migration, which is about 150,000 a year.
So the effect of it is, if our estimates our correct, that we will revert to net migration of 200,000 people every year.
This would place a severe strain on schools, housing and infrastructure in the UK.
Just over a third of all new households will be formed by migrants. This means that we'd have to build a home every seven minutes for the next 20 years to cope with the extra demand.
As for schools, already we're short of 120,000 primary school places for the start of the new school year. If immigration is allowed to continue these problems will continue and spread to secondary schools.
We are simply not prepared for migration on this scale, and the public certainly don't want to see it.