Barts Health, which runs Newham University Hospital, has been hit by a ‘cyber attack’ reported to be affecting NHS services across the country.

In a statement, the trust said: “We are experiencing a major IT disruption and there are delays at all of our hospitals.

“We have activated our major incident plan to make sure we can maintain the safety and welfare of patients.

“We are very sorry that we have to cancel routine appointments, and would ask members of the public to use other NHS services wherever possible.

“Ambulances are being diverted to neighbouring hospitals.”

The statement continued: “The problem is also affecting the switchboard at Newham Hospital but direct line phones are working.

“All our staff are working hard to minimise the impact and we will post regular updates on the website.”

Barts is one of 16 trusts across the country to confirm it had been targeted.

A spokesman for NHS Digital said: “A number of NHS organisations have reported to NHS Digital that they have been affected by a ransomware attack.

“The investigation is at an early stage but we believe the malware variant is Wanna Decryptor.

“At this stage we do not have any evidence that patient data has been accessed. We will continue to work with affected organisations to confirm this.

“NHS Digital is working closely with the National Cyber Security Centre, the Department of Health and NHS England to support affected organisations, ensure patient safety is protected and to recommend appropriate mitigations.”

He added: “This attack was not specifically targeted at the NHS and is affecting organisations from across a range of sectors.

“Our focus is on supporting organisations to manage the incident swiftly and decisively, but we will continue to communicate with NHS colleagues and will share more information as it becomes available.”

Pictures posted on social media showed screens of NHS computers with images demanding payment of 300 US dollars worth of the online currency Bitcoin, saying: “Ooops, your files have been encrypted!”

It adds: “Maybe you are looking for a way to recover your files, but do not waste your time.”

It demands payment in three days or the price is doubled, and if none is received in seven days the files will be deleted.