The 1.2m British expatriates living in EU countries face losing the right to stay in their properties year-round as well as the ability to work visa-free, lawyers and property experts say.

Although Britain could secure continued residency and work rights for them in its exit negotiations, expats are scrambling to obtain the citizenship of another EU nation as an insurance policy.

Spain has the most British expats, followed by Ireland, France, Germany and Italy, according to UN statistics cited by Full Fact, the fact-checking group.

“These expats do not face having their property confiscated or being immediately deported,” said George Peretz QC, an expert on EU law. “This would be a contravention of the European Convention on Human Rights.”

British citizens living in the EU are currently able to own property, work visa-free, access healthcare on the same terms as locals and draw their state pensions after retiring.

But Mr Peretz warned that unless the UK agreed to allow EU nationals to continue living in Britain after Brexit, a UK expat’s position would “become exactly the same as [that of] an American or an Argentine”.

He added: “Anyone British who is in a position to get citizenship of another EU country, through marriage or investment, would be well advised to do so.”

Eric Major, chief executive of Henley & Partners, which specialises in arranging investment visas into EU countries, said: “Since the referendum, we have had a number of inquiries from the UK of people wanting to explore whether their ancestry or lineage to Spain or Portugal can help them become citizens.”

There are various ways that expats can obtain an EU citizenship, even without the right ancestry.

In the UK, internet searches about how to obtain Cypriot citizenship have risen since April. Cyprus offers citizenship to individuals who invest €5m, or €2.5m as part of a collective scheme. Malta has a similar arrangement for those who deposit €650,000 into a government fund, as well as making other investments.

Chris Hadjikyriacou, the sales manager of BuySell, an agency that says it can process a Cypriot passport application within three months, said inquiries from Brits had been climbing since Friday’s referendum result.

“Yes we’ve had loads of British people calling,” he said, speaking from his office in Cyprus. “We have had about 15 serious inquiries since Brexit. We’ve never had them before and this is quite a lot in a few days considering you have to have €2.5m to invest [to obtain citizenship] . . . Before this, the majority of our inquiries came from China.”

Other countries, such as Spain and Greece, also offer wealthy investors long-stay residency rights.

On Monday, Ireland’s foreign minister appealed to people in the UK to stop rushing for Irish passports after a surge in applications threatened to stretch consular resources to breaking point.

Lucy Wadham, a British author who has lived in France since 1987, said she was applying for French citizenship for herself and the two of her four children who only have British passports.

“British expats who have lived for more than 15 years in Europe were not allowed to vote in the referendum. So I do not trust the government to negotiate effectively on our behalf,” said Ms Wadham, the author of books including The Secret Life of France.

“We have not been considered. And the results of this vote expressed the growing insularity of the British electorate.”

Heather Bedell, a British-born senior lecturer at the University of Applied Sciences and Arts of Southern Switzerland, said she felt “very lucky” to have already obtained Italian citizenship.

She commutes from Italy to her university, which is on the Swiss-Italian border. “Many of my British colleagues are applying for Italian citizenship too, and one is trying to get an Irish passport,” she said.

“Everyone is panicking and depressed. If we have to go down the sponsorship route [for British workers], it will be easier for employers to hire EU citizens who do not need work papers.”

British expats who already have dual citizenship of an EU country are counting themselves lucky.

British-born Helen Farrimond, 37, who moved to France 15 years ago after completing her degree at Birmingham University and marrying a French citizen, said: “I am one of the EU success stories, having come here, learned the language, become a dual citizen through marriage and found a good job in advertising.

“My children have both nationalities. Overnight after the referendum, it felt they have more possibilities for the future, to live and work across Europe, than my British friends’ children of the same age.”