A CYBER-ATTACK at Whipps Cross has forced the hospital to cancel appointments and divert ambulances.

Barts Health NHS Trust who runs the Leytonstone hospital was one of the worst affected by the global malware attack, which caused chaos at 45 NHS sites and in 100 different countries yesterday (May 12).

All outpatient appointments scheduled for today have been cancelled at all five of Barts's hospitals.

A spokesman for the trust said: “We are continuing to deal with a major IT disruption and we are sorry for any delays experienced at our hospitals.

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

“Some ambulances are being diverted to neighbouring hospitals and we are very sorry that we have had to cancel some routine appointments.

“All patients who have their appointment cancelled will be contacted as soon as possible to reschedule.”

A spokesman for Barking, Havering, and Redbridge University Hospitals Trust (BHRUT) told the Guardian its systems had been “largely unaffected”, but King George and Queen’s Hospitals were facing the “additional pressure” of patients from Whipps Cross.

He said: “Barts was very badly affected so that’s had a knock-on effect with us.

“We would ask all members of the public to only come to A&E unless it is an absolute emergency.”

Barts Health had to cancel 136 operations across its five hospitals, along with hundreds of chemotherapy appointments, because of another IT problem just two weeks ago (May 2).

The head of UK’s cyber security agency said experts are working “round the clock” to restore NHS systems, but there was no evidence of patient data being compromised.

The malware used to carry out the attack is called WannaCry and targets Windows operating systems.

It encrypts data files and blocks them from view before a screen appears demanding money to be able to access them.

The ransom is the equivalent of £230 in virtual currency Bitcoin.

The hackers have not yet been identified, but Home Secretary Amber Rudd said security services “must learn” from the attack.

Head of the National Cyber Security Centre, which is part of GCHQ, Ciaran Martin said: “It's important to understand that cyber attacks can be different from other forms of crime in that their sometimes highly technical and anonymous nature means it can take some time to understand how it worked, who was behind it and what the impact is.

"But our commitment is we will be as open as we can be, as soon as we can be, as our investigation continues."