The number of British citizens who have applied to acquire the nationality of another EU member state has surged since the Brexit referendum, data shows.

Since 2016 more than 350,000 UK citizens have opted to apply for the post-Brexit insurance policy, with some even forfeiting their British passport to retain their EU rights after Brexit.

The close historical ties between Ireland and the UK put the country top of the league of EU passports now held by dual-national Britons. But there have also been increases in Germany and France, where there has been a tenfold rise in naturalisation of British citizens.

In Spain, where dual nationality for British nationals is not a possibility, the numbers remain small but the rise since the referendum has also been sharp.

Just over 32,000 citizens in Northern Ireland and Great Britain applied to receive Irish passports in 2015 for the first time. This has quadrupled in the last four years with figures for 2019 showing 131,817 new applications for Irish passports, with nearly 55,000 from GB alone.

Table showing numbers of UK citizens acquiring Irish passports in past five years. Photograph: Department of Foreign Affairs and Trade

It means that between 2016 and 2020, nearly 360,000 people born in the UK have applied to acquire an EU passport across nine of the countries that supplied data.

The increase was dramatic, however, among those born in Great Britain who were applying for the first time for an Irish passport, rather than a renewal. The numbers rose from 7,372 in 2015 to 54,859 in 2019, according to data supplied for Ireland’s foreign affairs department.

In Spain, where the greatest concentration of Britons living elsewhere in the EU is found, the numbers who have taken up citizenship are marginal. Of the estimated 600,000 British people who live there just 209 applied for a Spanish passport in 2018, the last year for which data is available, but this is compared with just 50 applications in 2015 and 33 in 2016.

Although many thousands of Britons work in Brussels, the numbers for Belgium are also low. But they also show an upward trend since the referendum, with 1,403 naturalising in 2019 compared with 506 in 2016 and just 127 in 2015.

In Sweden the number of passports granted to Britons between 2016 and 2019 rose from 942 to 4,267, while in Germany they rocketed from 622 in 2015 to 6,640 in 2018, with figures for 2019 expected to show another increase as two Brexit deadlines came and went.

In France, where large numbers of British people live, the numbers are also relatively small but the pattern is the same: in 2015 just 320 Britons acquired French nationality; in 2019 that had increased to 3,827, according to government data.

Graph showing number of people from Britain who have got French passports since EU referendum. Photograph: French government statistics

The numbers in Italy have also grown steadily, with 266 applications in 2016 for an Italian passport rising to 731 the year after and 657 and 586 in 2018 and 2019.

Data for Denmark and Finland also show increases in the past four years although numbers remain in the hundreds.