"It will continue into the future so long as economic conditions are better here in the UK, where there is still relatively strong demand for labour.
"Once you have had immigration at these levels it will carry on for some time. That is because you will also get 'chain' migration because communities build up as people come to where they have friends and relatives."
Sir Andrew Green, chairman of MigrationWatch UK, said: "This is a significant increase in the number of south Europeans coming to Britain to search for work.
"Because we don't know how many are also going home, nor how long people are staying, we think the impact on overall immigration figures will be much less than these raw numbers.
"In the medium term, however, this is certainly a space to watch."
Registrations for NI numbers are used as an indicator of how many people are coming from overseas to work in this country.
The DWP's data showed a small rise in the number of eastern European immigrants applying for NI numbers was overshadowed by the surge in arrivals from the rest of the European Union.
According to the figures 209,000 eastern European immigrants were handed NI numbers last year, a one per cent rise on the previous 12 months, but other EU countries combined showed a 22 per cent jump, to 176,000.
New figures from the DWP also showed a 44 per cent rise in the number of Greeks coming to Britain to work, although numbers were far smaller at 8,680 last year
Separate figures published by the Office for National Statistics showed the number of people in the population who were born outside Britain reached 7,679,000 last year.
The total number of foreign-born residents has increased by 540,000 in just two years, and they now make up one in eight of the population.
In comparison, the figure was one in 11 in 2004, when there were 2.4 million fewer foreigners living in Britain.
Asylum applications are also on the rise, according to figures published yesterday, with an increase of 3,500 (18 per cent) in the year ending June this year.
In all there were 23,500 asylum applications with Syria accounting for the largest rise.