The Home Office is privately examining the possible impact of restrictions being lifted on Romanians and Bulgarians who want to live and work in Britain.
The Government privately acknowledges that the issue is politically toxic for the Coalition, pointing to signs that the UK Independence Party is seeking to exploit the subject by linking immigration to the European Union. Only limited numbers of people from either country are likely to travel to Britain next year when restrictions on the freedom of movement of citizens of the two newest EU member states are scrapped, senior government sources believe.
But the subject is preoccupying Whitehall, and the Foreign and Commonwealth Office (FCO) has commissioned private research on the likely demands on public services from newcomers.
Although the FCO has taken the lead on the issue, the Home Office has also been conducting internal talks on the potential effect of ending the restrictions next January. One of the issues on the agenda is whether Roma families could attempt to escape poverty and discrimination in Romania by heading to the UK.
Ministers are wary of releasing projections about the potential numbers of newcomers. One minister said: "I don't think you'll see us getting into the numbers game. It is really unknowable, but our sense is that the numbers coming here will be pretty low."
A separate Whitehall source said: "It's not possible and it would be unhelpful to say we anticipate x number of people to come to this part of the country at this time of the year. The consensus is that it would be incredibly imprecise."
Home Office officials believe Romanians are more likely to be drawn to Italy and Spain, where they have language links, and large settled communities are already in place. Nations such as Germany, Austria and Hungary could also prove attractive because of their proximity to Romania. Bulgarians are considered most likely to choose Greece or Spain to work.
The FCO commissioned the National Institute of Economic and Social Research to examine the possible effect of the lifting of "transitional controls" on Romania and Bulgaria. It has completed a draft report that is being considered by civil servants, who have been liaising with UK embassies in Bucharest and Sofia to examine any evidence of people preparing to seek work in Britain next year.