The Chief Executive of the Health Service Executive has said that he was "pleased" and "glad" to have the decryption key which has been provided by the cyber criminals who attacked its computer services last week.

However, Paul Reid said that there were no easy solutions and even with the key they were "a long way from being out of the woods just yet."

Speaking to RTÉ News, he said that "very significant checks" are being carried out on the key to make sure it is safe and secure.

Mr Reid also highlighted the challenges involved in rolling out any decryption tool.

He said that the HSE did not have a single location computer network, instead it had over 2,000 systems and over 4,000 servers across the country.

Mr Reid said it would take some time to work out how they would apply the codes to such a system.

He said: "First of all we have to see how do we do it safely and securely, how do we do it in a manner that doesn't further damage many of our services and many of our networks and that's a timeframe that is not known yet.

"This is not a simple process [taking] hours or days, this will still be a process over the coming weeks to seek to restore all of our services in a very safe way."

In relation to the court order secured by the HSE restraining any sharing, processing, selling or publishing of data stolen from its computer systems, Mr Reid described it as a "very strong order" and anyone who breaches will be in contempt of court and could face a criminal conviction.

Mr Reid said that social media companies had been "very supportive and collaborative" on this issue even aside from the High Court order.

"They will be watching for this and they will take [any stolen information] down," Mr Reid said.

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Earlier, Minister for Health Stephen Donnelly said progress has been made in getting some systems back in a number of voluntary hospitals following last week's cyber attack,

However, patients and health workers continue to face considerable disruption one week on from the attack on the Health Service Executive.

There are cancellations across all outpatient services with urgent radiation patients being contacted directly about their appointments and redirected to private hospitals for treatment.

Speaking on RTÉ's Morning Ireland today, Mr Donnelly said progress was made last night in getting some systems back in a number of voluntary hospitals.

This includes the National Integrated Medical Imaging System (NIMIS) radiology system, lab systems, and patient administration systems.

Mr Donnelly said radiation oncology "remains a problem" as disruption continues across many hospitals following the cyber attack.

While some machines are running, he said it is "not at the level" the HSE wants.

Meanwhile, technicians are checking the safety of a code sent by the hackers that may unlock the HSE's IT systems.

The HSE has said it now has a greater understanding of the scale and impact of the disruption last week's cyber attack has had on its IT and operational systems.

It said all elements of health services are affected, and a generalised slowing of clinical processes is capable of managing only lower volumes of activity.

In an affidavit to the High Court yesterday, MrReid said all HSE data is potentially compromised and the overall impact of the disruption on the HSE and patient care cannot be overstated.

There is no radiotherapy service currently operating at Beaumont, or St James's hospitals in Dublin, Galway University Hospital, and Cork University Hospital. There is limited radiotherapy services in St Luke's Hospital.

There are cancellations across all outpatient services, with daily outpatient services and scopes such as colonoscopies down by 70-80%, while chemotherapy and daily elective procedures are down by 50%.

Additional reporting George Lee