EU citizens should not be detained or refused entry to the UK if they are coming to Britain for a job interview, the government has confirmed.

The clarification of post-Brexit immigration rules was issued just days after it emerged that a Spanish woman had been locked in a holding room at Gatwick for 24 hours after telling border officials she was in London for an interview.

After a parliamentary question by Labour MP Hilary Benn, the immigration minister Kevin Foster said that such a reason for a visa-free visit to the UK was within the law.

“A person may come to the UK under the visitor route for a job interview.” He added that “if successful they must leave the UK and obtain an entry clearance under a route which grants the right to work in the UK before starting the role”.

According to the government website, “general business activities” allowed include “attending meetings, conferences, seminars, interviews”.

Alarming stories emerged last week of EU citizens being handcuffed at British airports, made to sleep in parked vans or prevented from accessing medication after being denied entry into the country under Brexit rules.

Benn, who now chairs the independent Brexit body, the UK Trade & Business Commission, said “cases of heavy-handed treatment of EU citizens coming into the UK to seek work will do nothing to help address labour shortages, or build a more constructive relationship with our European partners.”

The intervention by Benn comes amid increasing concern over a looming 30 June deadline for EU citizens already in the country to apply for settled status.

More than 50 parliamentarians have written to Boris Johnson urging him to extend the 30 June cut off date.

They warned that even if only 1% of the estimated 4 million EU citizens resident in the UK failed to apply, tens of thousands of people would become undocumented and vulnerable to hostile environment policies on 1 July.

Neale Hanvey, the Alba party MP who coordinated the cross-party letter, said: “The UK government cannot claim to be extending a hand of friendship to the world when in the early days of Brexit, they remove rights and status from EU citizens who have simply missed an administrative deadline for settled status.”

The Home Office came under fire again on Monday in the House of Lords after a number of long-term British citizens with dual EU nationality expressed alarm at receiving letters from the Home Office, telling them they risk losing the right to work, benefits and free healthcare unless they apply for UK immigration status in the next six weeks.

In an exchange with Brexit minister Lord Frost, Labour peer Lord Faulkner of Worcester asked: “Are you not worried the Home Office database is hopelessly inaccurate, and this is causing quite needless pain and alarm for people whose presence in Britain we really value?”.

Frost said the letter had been sent out as part of a “sensible” proactive drive to remind as many people as possible that the cut-off date was imminent.

While there were no plans to extend the 30 June deadline, Frost told the committee that the UK government would be “extremely understanding if for good reasons, reasonable reasons, individual citizens don’t register. There may be many good reasons why they don’t and are late, and we will be as pragmatic about that as we can. But in the end there has to be a deadline.”