- Boris Johnson's father is applying for EU citizenship, he said on Thursday.
- Stanley Johnson said he wanted to remain a full European after Brexit.
- Britain is due to leave EU trade and customs rules on New Year's Day.
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Boris Johnson's father Stanley is applying for French citizenship in order to maintain his rights as a European after Brexit, he said on Thursday.
"I will always be European that's for sure, he told RTL radio, according to Reuters.
"One cannot tell the British people: you are not Europeans. Having a tie with the European Union is important."
Johnson added that "I am French. My mother was born in France, her mother was totally French as was her grandfather. So for me, it is about reclaiming what I already have. And that makes me very happy."
The prime minister's father is a long-term pro-European and campaigned against leaving the European Union, despite his son fronting the campaign to leave it.
Stanley Johnson's comments come as Britain prepares to finally leave European trade and customs rules on New Year's Day, more than four years after the EU referendum result.
Under the terms of the prime minister's deal with the EU British people will no longer be free to live and work in Europe from Friday.
New costs and obligations will also be placed on businesses trading with the EU.
As a result, there has been a large increase in British citizens applying for passports and citizenship in European countries in order to bypass the new rules.
In particular, there has been a surge in demand for Irish passports, with the UK and Ireland already holding a common travel area.
Hundreds of thousands of British people have so far applied for Irish passports since the referendum result in 2016.