Spain has warned British tourists and second-home owners that they are not entitled to spend more than 90 days in the country at a time post-Brexit, but dismissed reports that offenders would be rounded up and deported if they overstay. Rules applying across the EU – which now apply to Britons – limit visa-free visits to those from outside the bloc to six months with an additional restriction of a maximum 90-day stay per 180-day period. While the visitor rules do not apply to British nationals settled in the EU lawfully, hundreds if not thousands of unregistered British citizens in Spain could be affected. “These are people who have been flying under the radar for a long time when they should have registered their residence in the country and didn’t for whatever reason,” said Sue Wilson, the chair of Bremain in Spain, a group campaigning for the rights of British migrants living in Spain. “If they are unable to prove they were resident before 31 December and get entitlement to remain in Spain, they now face a 90-day deadline to leave the country. “Many are still planning to do the same and think the Spanish will either turn a blind eye or will take time to get their act together to enforce the law. But they are kidding themselves. These rules are rules that have applied to third-country nationals for years and the Spanish authorities have no catching up to do.” Spanish government sources have lamented what they say are misleading reports in UK media suggesting they will be “deporting” or “kicking out” 500 British nationals in the coming days. The Guardian understands that police will not be deployed to search for British over-stayers, but that anyone staying longer than 90 days will be considered to be in an irregular situation and will be subject to the law if they are picked up at a control point. British nationals living lawfully in Spain before 31 December are entitled to remain in the country permanently under the Brexit deal. However, the new rules are causing anxiety and stress to some who face having to choose their formal country of residency. “If they remain in Spain, they have to become officially resident and might be worried about their rights to go home to access the NHS for example. For them it is crunch time,” said one British national in Spain who did not wish to be named. Michele Euesden, the Marbella-based managing director of the Euro Weekly newspaper, said there had been a surge in the number of people moving “lock, stock and barrel” back to the UK before they breached their 90-day limit. “Some people are frightened of the consequences if they overstay and are afraid if there is another lockdown they will won’t be able to leave and come back again and visit because they will be known to the authorities,” said Euesden, who also offers a one-stop shop for movers to and from Spain. She added that the departure of people who had “lived under the radar for 20/30/40 years” and who “contributed nothing” in the way of taxes or social contributions would not be missed. A spokesman for Spain’s interior ministry said there were errors in media reports that suggested the government was planning mass deportations of unregistered Britons. “Following the UK’s departure from the European Union, and in accordance with the Brexit agreement with EU countries and international conventions, British citizens are subject to the same rules as citizens of other third-party countries,” he said. “Like any other third-country citizens, the maximum period they can stay in Spain is three months – unless they have a work, study, or other kind of visa that allows them to stay longer.” Government sources said Spain was merely following the rules governing visits and stays in its territory that apply to the UK as a non-EU country. The government guidelines state: “Stays in Spain cannot exceed 90 days in an 180-day period, whether in a single visit or various visits. Britons need to use their passports for identification purposes and will be exempt from visas.” The interior ministry also pointed out that fewer Britons were visiting Spain at the moment because of Covid travel restrictions, which will end on Tuesday. Spain introduced the curbs on 22 December last year in response to the spread of the so-called British strain of coronavirus, allowing entry only to flights and ships carrying Spanish and Andorran citizens or official residents. The restrictions will be lifted on 30 March, but those arriving from the UK will still have to show a negative PCR result from a test taken no more than 72 hours before arrival.