Foreign doctors and nurses are increasingly choosing not to work in the NHS because anti-migrant rhetoric and rising racism are creating a “hostile environment” in the UK, the chair of the Academy of Medical Royal Colleges has warned, saying the health service could “quite easily fall over” without overseas staff.

Jeanette Dickson, an NHS consultant clinical oncologist who leads the body representing the professional interests of about 220,000 doctors across the UK and Ireland, said international recruitment was being undermined by the tone of political and media debate about migration, alongside reported racist abuse directed at overseas clinicians by colleagues and patients.

“The NHS would collapse within hours,” she said of the service’s reliance on staff from abroad, warning that significant departures could leave hospitals and other services without “a critical mass of people there to run the service safely”.

Her remarks come amid signs, based on professional regulator workforce data, that fewer overseas health workers are arriving and more are leaving. Dickson said record numbers of foreign-born doctors were quitting the NHS, the surge in recruitment after Brexit had stalled, and the number of nurses and midwives joining the health service had fallen sharply over the past year.

The NHS has depended on overseas workers since its creation in 1948, but that reliance is now at its highest level, with General Medical Council figures showing 42% of doctors in the UK qualified abroad.

Dickson said overseas clinicians who have never visited the UK may be deterred by what they see in British politics, social media and news coverage. “My feeling is we are creating a culture where the rhetoric is ‘foreigner bad’,” she said. “If you have never visited Britain and are looking at our media, the social media, press media, print media, what our politicians are reported as saying, I think that it’s not unreasonable to see that as a hostile environment.”

She linked the perceptions of hostility to broader developments, including Brexit and public debate about immigration, and said international medics could look elsewhere when deciding where to build their careers. “Why would you go somewhere where people are going, ‘we don’t need you, we don’t want you’?” she said, adding that this could make Britain appear “unwelcoming” and “racist”. She said the prevalence of hostility to migrants was “significantly more” than a decade ago.

The concerns are not limited to recruitment, Dickson said, but also involve the everyday safety and wellbeing of existing staff. She pointed to examples of racist aggression directed at minority ethnic NHS workers, including incidents described publicly by NHS leaders.

Selina Douglas, the chief executive of the Whittington health trust in London, told a public meeting last month that staff were experiencing a rise in racism. Referring to overseas nurses who have worked in the UK for 25 years, Douglas said: “Those staff are being racially abused in our hospital. I have had staff spat at walking up the hill [from the tube station].”

The health secretary, Wes Streeting, also addressed abuse of NHS staff last month, saying: “Your right to access free healthcare in this country does not come with the freedom to abuse our staff on any grounds.” However, Dickson questioned what practical action is taken in response to abuse, including whether NHS trusts or police consistently pursue cases.

Dickson also criticised the government’s approach to allocating specialist training posts, arguing that prioritising UK medical graduates over overseas-qualified doctors could deter international clinicians at a time of global staff shortages and intense competition. She said doctors and nurses have “portable skills” and may choose countries such as Canada, Australia and New Zealand if they are perceived as more welcoming and offer better working conditions.

“There’s always been a cohort [of doctors] who’ve gone back to their country of origin or another country,” she said, adding that she was more concerned by signs that the number of overseas graduates wanting to enter the UK was diminishing.

In response, a Department of Health and Social Care spokesperson said: “The NHS benefits hugely from its international staff, and we’ll continue to support and attract talented overseas staff who want to dedicate their time, energy and skills to the health service.”

The spokesperson added: “Discrimination against patients and staff alike undermines everything our health service stands for – and the NHS has a zero tolerance for racism.” They also said reliance on international recruitment reflected a failure to train enough staff in the past and defended plans to prioritise UK graduates for speciality training roles so taxpayers “see a return on the investment” in domestic medical training.

Dickson urged ministers, including the prime minister, Keir Starmer, to make clear publicly that overseas doctors and nurses are welcome, warning that continued hostile rhetoric, combined with outward migration, could push the NHS towards unsafe staffing levels.