Fewer EU citizens are registering for National Insurance numbers in Swindon than before the Brexit vote, new figures reveal.

The statistics, from the Department for Work & Pensions, show how many foreign nationals have successfully applied for NI numbers, which are required to work or claim benefits.

In the 12 months up to March this year 1,617 people from the EU registered for NI numbers.

In the year before June 2016, the month of the referendum, 1,954 people registered, 337 more than in the latest period.

The data divides the European workers into three groups.

It identifies people from the EU15, which are countries that joined the bloc before 2004, like France, Spain and Germany.

The EU8 countries joined in the 2004 enlargement, and include nations such as Poland and the Czech Republic.

The EU2, Romania and Bulgaria, joined in 2007, but could not move to the UK to work until 2014.

The biggest drop in new workers registering post Brexit was by those from the EU8 countries. In the 12 months up to March, 295 EU8 citizens signed up for NI numbers, 250 fewer than before the Brexit vote. Of residents from the EU15, 75 fewer registered. And the number of Romanians and Bulgarians registering for NI numbers, reduced by 14 or 3 per cent.

The data does not explain why the numbers have reduced.

It could be due to post-Brexit uncertainty or other factors such as the improvement of the economies in residents’ home countries. Poland, for example, currently has a record low unemployment rate.

The number of applicants from outside the EU has also decreased.

A total of 1,084 people from the rest of the world registered for NI numbers in the 12 months up to March, a drop of 11 on the period before Brexit. From outside of Europe, the region with the highest number of applications was South Asia, which includes India and Pakistan, with 701 registrations.

This, combined with a drop in the number of EU citizens applying, has contributed to a reduction in the overall number of foreign nationals applying for NI numbers in Swindon. In the 12 months up to March a total of 2,705 people gained an NI number, a decrease of 341 on the 12 months before the Brexit vote.

There has been concern that there will be a workforce gap after Brexit, particularly in catering, construction and agriculture.

The justice secretary David Gauke said prisoners could fill the roles that migrant workers had left behind.

The DWP said the figures should not be used to indicate immigration levels, as foreign nationals could have been in the country for some time before applying for an NI number.

According to the ONS’ latest nationwide immigration statistics Romanians moved above Irish and Indians to become the second most common non-British nationality in the UK, after Poles.