An unprecedented influx of immigrants from Eastern Europe has swollen the population of Sussex towns, new figures have revealed.

The impact of the new arrivals on small and medium-sized communities is shown in the Government statistics released under the Freedom of Information Act.

In Arun, the number of Eastern Europeans who have registered to work is 2,803.

The district has seen its population increase by two per cent and has the third highest number of Eastern Europeans in the South East.

In Brighton and Hove 2,286 registered Eastern Europeans have swelled the population by one per cent - giving it the fourth highest population.

There are now 67,649 Eastern Europeans registered to work in the South East, accounting for a 0.8 per cent rise in the population.

The dramatic change has happened in only 18 months, following the controversial expansion of the EU eastwards in May 2004 and could continue to rise in coming weeks and months.

Even these figures are likely to be a dramatic underestimate, as they do not include children or partners of those registered to work by the Home Office. Self-employed workers such as plumbers are also missing from the list.

Union bosses have given a cautious welcome to the influx but warned it could lead to major instability for the economy.

A spokesman for the South East GMB, the general workers union, said: "Immigration on the scale which has been seen in Sussex can be a very positive thing because it fills jobs which are currently vacant. But there are concerns.

"It can rob residents of jobs too and immigration which gets out of control can overheat the economy and lead to a collapse."

The influx has led to a major rise in the popularity of political groups like the British National Party.

Arun District Council was so concerned about the rise of BNP "propaganda" in Bognor earlier this year, it distributed its own counter propaganda attempting to dispel some of the myths surrounding immigration.

Bognor and Littlehampton MP Nick Gibb decline to comment on the current situation.

Mass immigration has led to some pubs in the Arun district barring Eastern Europeans.

Conversely it has also led to a rise in demand for European language courses.

Sue Johnston, who runs private tuition Polish courses in Bognor, said: "My revenues have gone up 100 per cent in the last three years because many shop owners and businesses need to converse in the language."

Job agencies have also begun to post job adverts in several languages.

The Citizen Advice Bureau revealed it is seeing a growing number of people worried about losing their jobs because of immigration.

A Sussex spokesman said: "We have spoken to a number of clients who are worried about redundancy.

"Immigration has positive benefits but the fact we are seeing people who fear losing their jobs is evidence that the system does not always work."

The figures reveal the exact destinations of immigrants who signed the Home Office's Worker Registration Scheme (WRS) between May 2004 and December 2006.

Ministers had previously refused to reveal anything more than crude geographic locations.

Experts believe the true total is between 30 and 50 per cent higher than those listed - which will make the full impact significantly more dramatic.