The number of people with at least two different passports in Ceredigion and Powys has increased in the last decade, new figures show.
A rise in the number of dual citizens across England and Wales is thought to have been driven by migration over the past decade, with more people moving to the UK from the EU.
Additionally, many eligible people with UK passports have taken up extra ones after Brexit.
Census 2021 figures show there were around 830 UK and non-UK born people in Ceredigion who had multiple passports in 2021 – an increase on 522 people 10 years earlier, when the previous census took place.
They accounted for 1.2 per cent of all people in the area – up on 0.7 per cent in 2011.
And there were around 1,185 UK and non-UK born people in Powys who had multiple passports in 2021 – an increase on 649 people. They accounted for 0.9 per cent of people in the area – up from 0.5 per cent.
Across England and Wales, the number rose from 612,000 (1.1 per cent) in 2011 to 1.26 million (2.1 per cent) people who held multiple passports in 2021.
In both counties there was a substantial increase in those born in the UK who had both Irish and UK passports, with 155 in Ceredigion, compared to only 36 in 2011, and 240 in Powys, compared to only 54 10 years earlier.
Overall, this trend was mostly noticed in people aged 50 to 70 years old, which the Office for National Statistics suggested is because many only took up their dual nationality more recently despite moving to England and Wales years ago.
There were also 195 people who held EU and UK passports in Ceredigion in 2021, which was an increase on 48 with both passports a decade ago. In Powys, that figure was 185, up from 45.
Jay Lindop, from the ONS, said: “This change has been partly driven by migration over the decade, with an increase in people moving here from the EU. As people who have settled in England and Wales go on to have children, we can see an increase in dual citizenship among the younger ages.
“The rise in dual citizens may also suggest greater uptake of additional passports following the end of free movement when the UK left the European Union.”
Those who held a non-UK passport only, which includes EU, non-EU and Irish passports, accounted for 4.6 per cent of all people in Ceredigion, while those who only had a UK passport made up for 70.7 per cent of the population in the area.
In Powys, 2.7 per cent of all people held a non-UK passport only, while those who only had a UK passport made up for 74.4 per cent of the population.