LONDON (Reuters) - The most disruptive cyber attack in the history of Britain's National Health Service propelled a debate over state hospital funding to the center of the election campaign on Monday, though officials said there had been no second wave of infections.
The "WannaCry" worm global attack, which locks computers and demands a $300 ransom, sowed chaos on Friday through the computer systems of some NHS hospitals which canceled operations and reduced non-emergency care.
Although experts had voiced fears that a second wave of attacks could strike systems on Monday, the British authorities said this appeared to have been avoided.
"Across the globe, events today have been at the lower end of our expectations," said Ciaran Martin, the head of the National Cyber Security Centre which is part of Britain's surveillance spy agency GCHQ.
"We're continuing to investigate a small number of potential cases but there is nothing new to report," Martin said.
Scores of organizations inside the NHS, which provides free medical care for all and is a source of pride for Britons, were hit by the ransomware on Friday.
On Monday, the opposition Labour Party said Prime Minister Theresa May's response to the crisis had been poor and her government was to blame for failing to invest to keep the service secure.
Some hospitals still asked patients on Monday to seek treatment only for life-threatening emergencies.
Opinion polls show the NHS is the issue voters care most about, ahead even of Britain's exit from the European Union and the economy, before the June 8 national election.
"The government's response has been chaotic, to be frank," Labour's health spokesman Jon Ashworth said. "They've complacently dismissed warnings which experts, we now understand, have made in recent weeks.
"The truth is, if you're going to cut infrastructure budgets and if you're not going to allow the NHS to invest in upgrading its IT, then you are going to leave hospitals wide open to this sort of attack," he added.
Britain spends about 145 billion pounds ($187 billion) a year on health, or about a fifth of its state budget. Spending is projected to rise in real terms, although Labour says the government's plans do not provide enough to prevent a looming health crisis due to an ageing population.
The NHS, which was showcased in the opening ceremony of the 2012 Olympic Games, employs more than 1.5 million people, making it the world's fifth biggest employer after the U.S. and Chinese militaries, Walmart and McDonald's.
Officials struggled to explain why some NHS computers had not been "patched" with Microsoft updates to close the vulnerability that allowed the worm to spread across its networks.
"There are things you can do that everyone can do (...) in particular making sure that our data is properly backed up and making sure that we are using the software patches," said Health Secretary Jeremy Hunt.
Security Minister Ben Wallace said the government used to contract for computer services across the entire NHS but that in 2007 - when the Labour Party was in power - that was stopped and left to the local trusts that run hospitals.
In a snap election campaign which May has dominated so far, the debate over the cyber attack on the NHS forced her onto the defensive, although it was not immediately clear what impact, if any, it would have on her popularity.
Britain's spending watchdog, the National Audit Office, warned in 2014 that some NHS organizations had "limited understanding of the threat and they do not yet understand what would represent an appropriate level of threat protection".
Asked if the government had ignored warnings over the NHS being at risk from cyber attack, May told Sky News: "No. It was clear (that) warnings were given to hospital trusts."
She said the attack had not been focused on the NHS but was part of a wide international issue, and said the government had invested 2 billion pounds in cyber security.
"We take cyber security seriously," said May, who was responsible for domestic security for six years as home secretary before becoming prime minister last year.
A poll on Monday found three-quarters of Britons thought the NHS was in a bad condition and more than 50 percent blamed the Conservatives for its current woes.
Government ministers were due to hold an emergency response meeting later on Monday to deal with the crisis. A spokesman for May said the annual information technology budget in the NHS was 4.2 billion pounds and that an extra 50 million pounds had been allocated for updating cyber security.
Additional reporting by Michael Holden, Elizabeth Piper, and Andy Bruce; Editing by Alison Williams and Peter Graff