The NHS is a valuable national asset – and not just in terms of the lives it saves.

Last week the tensions between the health service’s role as a collective national endeavour and its potential as a source of private sector profit flared again, following a characteristically blunt intervention from the US president. Donald Trump’s claim, later retracted, that the NHS would be “on the table” in US-UK trade talks underlined the organisation’s enduring appeal to the private sector.

Data is one the areas of interest to commercial players. The NHS database holds the medical records of 65 million people and is drawing the attention of private businesses.

While other countries’ datasets are more fragmented, the NHS database has comprehensive patient records that go back decades. This treasure trove is priceless to technology giants such as Google’s parent Alphabet as well as smaller healthcare firms, which are vying to develop health mobile phone apps that perform a host of tasks from monitoring vital organs to carrying out an initial diagnosis.

Industry experts say the NHS number – the unique 10-digit code attached to every patient and their records – means the UK’s health service has a superior dataset that includes information such as patients’ medication needs, allergies, vaccinations, previous illnesses, test results and hospital discharge summaries. “Until very recently a lot of it was paper-based but as more data is digitised it will become increasingly valuable,” says Julie Simmonds, a healthcare analyst at the stockbroker Panmure Gordon.

“It is very valuable for a pharma company. Real world data is better than clinical data.” Outlining the obvious concerns, she adds: “It’s how you access that and use it in an ethical way – it’s going to create concerns.”

DeepMind Health, the London-based artificial intelligence company owned by Alphabet, was one of the first to develop a product based on NHS data. In 2016 it launched a mobile phone app, Streams, that detects early signs of kidney failure in patients. The app, used at London’s Royal Free hospital, pulls together medical information, such as patients’ blood test results, and sends alerts to doctors if the results suggest a patient could develop acute kidney injury, which is a condition linked to 100,000 deaths in the UK every year.

Alphabet’s push into UK healthcare was soon at the forefront of expressions of unease over the use of patient data. Last July the Information Commissioner’s Office found the Royal Free hospital broke data protection rules when it gave details from 1.6 million patients to DeepMind without informing patients adequately. DeepMind, which used the patient data to test the Streams app, said at the time that it had made mistakes.

There are other concerns. Streams is being expanded to include alerts for more conditions such as sepsis and other organ failures, and is being rolled out across the UK. DeepMind also wants to distribute it globally. This has alarmed one competitor, who believes DeepMind is using a public asset to build and refine a commercial product that will make significant sums once it is sold to consumers worldwide.

The former UK science and defence minister Lord Drayson, who runs the AI healthcare firm Sensyne Health, has expressed concerns that Google is able to access the NHS’s database for free to develop healthcare apps that it will roll out around the world.

The Labour peer says: “NHS data is world-class and a national asset of the UK, potentially worth billions, that could help to fund NHS services in future. Big tech companies shouldn’t be able to access NHS data for free.”

Drayson, who wants new regulation to safeguard the proper use of patients’ medical records, adds: “This is a sector that is going to be enormous in the future. In other countries the datasets are fragmented. The NHS dataset is across the social spectrum, from birth to death … That’s why Google is here.”

A DeepMind spokesperson said: “There are many ways we recognise and return value to our NHS partners, for example by improving and advancing hospital data sets for future research and offering free access to resulting technology.

“Trust data remains under the control of our NHS partners and we can only process it in accordance with their instructions.”

Sensyne is also partnering with the NHS to create products that could become global sellers but is offering a cut of the rewards. The Oxford-based firm has struck several partnerships with NHS trusts to develop smartphone apps that monitor heart conditions, lung disease and diabetes in pregnant women. Six NHS trusts have been given shares in Sensyne in return for providing anonymised patient data and will receive 4% of future royalties from any products developed.

Consultants at EY believe that if the NHS put its vast database to use, by employing artificial intelligence to develop health apps and improve patient treatment, this could generate a £4.6bn benefit to the wider economy because people would be healthier and fitter, taking fewer sick days and working more efficiently.

Rather than programming systems manually to detect signs of illness – a hard task because of the number of different factors at play – AI systems can be trained to learn how to interpret test results, and which types of treatments are best for individual patients.

Other companies muscling into the lucrative health technology market include apps such as Babylon Health, Push Doctor and Now GP, which offer video consultations with GPs. Babylon currently offers its app in London, through the Hammersmith & Fulham clinical commissioning group (CCG). It means users, who need to live or work within 30-40 minutes of the practice, deregister from their NHS GP practice to join Babylon’s GP at Hand service.

More than 52,000 people across London have signed up for the Babylon app, which has been championed by Matt Hancock, the health secretary. The Hammersmith and Fulham CCG faces a £21.6m funding gap because it has to pay for the healthcare of all patients registered with the app, even if they do not live in that area.

The CCG expects NHS England to reimburse those costs. It commissioned a report to evaluate GP at Hand, which said it “raises questions about the financial impact of the service on the wider health system”. The local council’s cabinet member for health warned Hancock that it could ultimately lead to practice closures in Hammersmith and Fulham.

As the wealth and expertise of tech firms expands, and funding pressures on the NHS increase, the interaction between NHS data and the commercial sector is set to grow. The controversy, and the opportunities for life-changing products, will not go away.