Major London hospitals cancelled some operations on Tuesday after a cyber-attack on a key service supplier had a major impact, particularly on blood transfusions, the National Health Service (NHS) said.

The attack on pathology partner Synnovis hit Kings College Hospital and Guys and St Thomas in the centre of the British capital.

On Monday 3 June Synnovis, a provider of lab services, was the victim of a ransomware cyber attack, said a spokesperson for NHS England, London region.

This is having a significant impact on the delivery of services at Guys and St Thomas, Kings College Hospital NHS Foundation Trusts and primary care services, they added.

Ian Abbs, CEO of Guys and St Thomas NHS Foundation Trust, earlier wrote in a staff memo that the attack was 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, he added.

The Health Service Journal (HSJ) trade publication reported that it could take weeks, not days to access pathology results, according to a senior source.(AFP: London Hospitals Hit By Cyber Attack)