Patients seeking urgent healthcare at NHS hospitals in London have been redirected elsewhere after a "major" cyber-attack crippled facilities at the last minute.

A critical incident spanning facilities run by the Guy's and St Thomas' Trust and King's College Hospital meant Britons in need of vital treatment couldn't receive it - in particular, those in need of blood transfusions, after the cyber-attack knocked out pathology labs' IT systems connected to NHS-contracted firm Synnovis.

The Guy's and St Thomas'-run Royal Brompton and Harefield has reportedly been forced into cancelling potentially life-saving transplants, with the Evelina London Children's Hospital also affected by the attack.

The cyber-attack reportedly began yesterday, but is now affecting hospitals across the capital.

The Guy's and St Thomas' trust was among those affected

One email sent to staff at King's College Hospital read: "This is having a major impact on the delivery of our services, with blood transfusions being particularly affected.

"Some activity has already been cancelled or redirected to other providers at short notice as we prioritise the clinical work that we are able to safely carry out.

"I recognise how upsetting this is for patients and families whose care has been affected, and how difficult and frustrating this is for you all. I am very sorry for the disruption this is causing.

"An incident response structure has been stood up, with colleagues from across the Trust meeting regularly to assess the situation and put contingency plans into place.

The cyber-attack reportedly hit systems run by NHS-contracted IT firm Synnovis (file photo)

"While we do not yet know all the details or how long this issue will take to resolve we will keep you updated through the usual routes, including through the clinical alert system."

GB News has approached NHS England and the Department for Health and Social Care for comment.