NHS keyboard
IT email: 'Google is intermittently blocking access due to the amount of traffic from NHS Trusts' iStock

Staffers on the UK's National Health Service (NHS) networks are reportedly having trouble using Google services because the internet giant is mistakenly identifying the amount of traffic being generated as a botnet – a malicious collection of hacked computers.

In an internal email, headed "Google Access", an NHS trust IT worker confirmed the health service's networks – used by roughly 1.3 million employees – were bring blocked, at least until the user entered additional information to prove they were human.

"Google is intermittently blocking access due to the amount of traffic from NHS Trusts nationally (This is not being blocked by the IT department). This is causing Google to think it is suffering from a cyberattack," read the email, obtained by The Register.

It added: "We are advising staff to use an alternative search engine i.e. Bing to bypass this problem. If you have 'Chrome' on your desktop the page will display correctly but if you should get a Captcha pop up, please follow the instructions to continue."

In a statement, an NHS digital spokesperson said: "We are aware of the current issue concerning NHS IP addresses which occasionally results in users being directed to a simple verification form when accessing Google."

The statement continued: "This would appear to be due to the high number of people using our systems and trying to access Google at peak times. We are currently in discussion with Google as to how we can help them to resolve the issue."

A Google spokesperson said: "Our systems are simply checking that searches are being carried out by humans and not by robots in order to keep web users safe. Once a user has filled out the Captcha they can continue to use Google as normal."

Botnet traffic can be used in large-scale cyberattacks. In one example last year a botnet called Mirai was able to take down large swathes of the internet in the US, after it was powered by a slew of hacked internet-of-things (IoT) devices including CCTV cameras and routers.

Google and the NHS have a strong working relationship. Last year, the two partnered to produce landmark research using the web giant's DeepMind artificial intelligence department. The NHS handed Google 1.6 million hospital records to work with.

Yet the British health service has come under fire in the past for its cybersecurity protections. In one study, based on Freedom of Information (FoI) requests, it emerged that seven trusts failed to spend a single penny on online security in 2015.

The service was also hit with a slew of ransomware attacks over the past 12 months. In one major incident, roughly 1,000 patients were impacted by cancellations at three hospital facilities as they were forced to shut down vital computers used for administration.