A virus and spyware warning message on a laptop screen at a home in London, following a major cyber attack on NHS computer systems

Police in Northern Ireland are working closely with government and tech agencies amid fresh warnings that the cyber attack that crippled international services are set to continue.

Europol has warned that the threat "will continue to grow" as people return to work on Monday. Since Friday's breach more than 200,000 victims - including the NHS - across 150 countries have been infected by the Wanna Decryptor ransomware, also known as WannaCry.

Latest advice and patches are available from the National Cyber Securty Centre

The PSNI has said it has been liaising with relevant agencies "to ensure that here in Northern Ireland we are adequately briefed and prepared for the possibility of any potential similar incident."

Detective Chief Inspector Douglas Grant said: "Since this attack occurred on Friday afternoon we have been working with representatives from the national government, National Crime Agency, National Cyber Security Centre and cyber security experts to put in place mechanisms to mitigate the risk to systems in Northern Ireland.

"As people return to work tomorrow after the weekend, many will have unopened, potentially infected emails in their inboxes, or their systems may already be infected and are waiting to activate. It is of the utmost importance that individuals and organisations act to ensure the integrity of our local cyber networks and take appropriate action to reduce the threat posed by cyber criminals."

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"While there is currently no suggestion that systems within Northern Ireland have been targeted, we remain conscious that we must act to ensure the integrity of cyber networks and take appropriate action to reduce the threat posed by cyber criminals.

"Do not open emails from unknown sources or containing suspicious links or attachments. Ensure that all computers on your network are fully updated with the latest 'patches'. A ‘patch’ is a piece of software designed to update a computer program or its supporting data, to fix or improve it. This includes fixing security vulnerabilities."

Speaking to ITV's Peston on Sunday, Europol director Rob Wainwright said the attack was indiscriminate across the private and public sectors.

"At the moment we are in the face of an escalating threat, the numbers are going up, I am worried about how the numbers will continue to grow when people go to work and turn their machines on Monday morning.

"The latest count is over 200,000 victims in at least 150 countries. Many of those will be businesses including large corporations."

Organisations across the globe, including investigators from the National Crime Agency (NCA), are now working non-stop to hunt down those responsible for the ransomware.

Meanwhile health authorities are racing to upgrade security software amid fears hackers could exploit the same vulnerability with a new virus.

There have been calls for an inquiry into the circumstances surrounding Friday's major incident, with the Government and NHS chiefs facing questions over their preparedness and the robustness of vital systems.

Mr Wainwright explained: "We have been concerned for some time. The healthcare centres in many countries are particularly vulnerable. They are processing a lot of sensitive data."

A British cyber whiz was hailed an "accidental hero" after he registered a domain name that unexpectedly stopped the spread of the virus, which exploits a vulnerability in Microsoft Windows software.

The anonymous specialist, known only as MalwareTech, prevented more than 100,000 computers across the globe from being infected.

On Sunday MalwareTech issued a warning that hackers could upgrade the virus to remove the kill switch.

"Version 1 of WannaCrypt was stoppable but version 2.0 will likely remove the flaw. You're only safe if you patch ASAP," he wrote on Twitter.

A number of hospitals in England and Scotland were forced to cancel procedures after dozens of NHS systems were brought down in Friday's attack.

Medical staff reported seeing computers go down "one by one" as the attack took hold, locking machines and demanding money to release the data.

Around a fifth of trusts were hit amid concerns networks were left vulnerable because they were still using outdated Windows XP software.

The apparent chink in the NHS's defences led to criticism of the Government and NHS bosses, with the Liberal Democrats demanding an inquiry takes place.

Speaking after a Cobra meeting on Saturday, Home Secretary Amber Rudd admitted "there's always more" that can be done to protect against viruses.

She said: "If you look at who's been impacted by this virus, it's a huge variety across different industries and across international governments.

"This is a virus that attacked Windows platforms. The fact is the NHS has fallen victim to this.

"I don't think it's to do with that preparedness. There's always more we can all do to make sure we're secure against viruses, but I think there have already been good preparations in place by the NHS to make sure they were ready for this sort of attack."

Labour's shadow health secretary, Jonathan Ashworth, in a letter to Mr Hunt, said concerns were repeatedly flagged about outdated computer systems.

Speaking to Robert Peston, he demanded that the Conservatives publish the Department of Health's risk register to see how seriously they were taking IT threats.

Among those affected by the virus was Nissan UK, but the car manufacturer said there had been no major impact.

It is understood its plant in Sunderland is not due to have another production shift until Sunday night.