North Korea may be behind the huge global hack that took down the NHS, experts have said.

The hack took down important computers across the world and might even be responsible for deaths in affected hospitals. But an international manhunt for the people behind it is still ongoing – with very few clues about who was responsible.

Those behind the attack asked for money to unlock the computers that were caught up in it. But some have speculated that the code might have got out by mistake – and that it was never really meant to be used to hold computers to ransom at all.

Life in North Korea captured with a mobile phone Show all 30 1 /30 Life in North Korea captured with a mobile phone Life in North Korea captured with a mobile phone Farmer works in a field Getty Images Life in North Korea captured with a mobile phone Women soldier walk on the street Getty Images Life in North Korea captured with a mobile phone A female soldier guards railway Getty Images Life in North Korea captured with a mobile phone A general view of platform of Pyongyang Railway Station Getty Images Life in North Korea captured with a mobile phone Students stage a protest against South Korea and the US in Pyongyang Getty Images Life in North Korea captured with a mobile phone Students rehearsal for celebrating the 70th birthday of Workers' Party of Korea Getty Images Life in North Korea captured with a mobile phone People enjoy the cool at the carriage door Getty Images Life in North Korea captured with a mobile phone A general view of countryside Getty Images Life in North Korea captured with a mobile phone Korean People's Army soldier rest on the rail 2015 Getty Images Life in North Korea captured with a mobile phone A little boy begs food on the platform in Hamhung Railway Station in Hamhung 2015 Getty Images Life in North Korea captured with a mobile phone Children swim in a river in noon Getty Images Life in North Korea captured with a mobile phone People cross a railway crossing 2015 Getty Images Life in North Korea captured with a mobile phone A boy collects corn cob beside a railway Getty Images Life in North Korea captured with a mobile phone A customs officer is seen on the train No.100 from Moscow to Pyongyang at Tumangang railway station in Tumangang Getty Images Life in North Korea captured with a mobile phone A customs officer checks a passenger's mobile device on the train to Pyongyang Getty Images Life in North Korea captured with a mobile phone A railway station in Tumangang Getty Images Life in North Korea captured with a mobile phone A general view of the railway station in Tumangang Getty Images Life in North Korea captured with a mobile phone Kids pass by Tumanggang railway station in Tumanggang 2015 Getty Images Life in North Korea captured with a mobile phone A general view of Tumangang Getty Images Life in North Korea captured with a mobile phone A general view of Tumangang - a small town located at North Korea and Russia border Getty Images Life in North Korea captured with a mobile phone A train carriage on it's way to Pyongyang is delayed for a day and half due to military transportation in Tumangang Getty Images Life in North Korea captured with a mobile phone A customs officers talks to a passenger at Tumanggang railway station in Tumanggang Getty Images Life in North Korea captured with a mobile phone A little girl walks on the street in Tumanggang 2015 Getty Images Life in North Korea captured with a mobile phone An elderly man is seen in Tumangang Getty Images Life in North Korea captured with a mobile phone Kids go to school in morning in Tumangang 2015 Getty Images Life in North Korea captured with a mobile phone Life in North Korea captured with a mobile phone Life in North Korea captured with a mobile phone Life in North Korea captured with a mobile phone Life in North Korea captured with a mobile phone

Cyber security experts are now pointing to North Korea as the source of the hack – just the latest in globally disruptive cyber attacks that the country has been blamed for.

Experts said that the code used as well as the way that the hackers took computers hostage were similar to the way that North Korea has worked in the past.

Simon Choi, a director at anti-virus software company Hauri Inc, said Tuesday that North Korea is no newcomer in the world of Bitcoin and it has been mining Bitcoin using malicious computer programs as early as 2013.

Last year, Choi accidentally spoke to a hacker traced to a Pyongyang internet address about development of ransomware and he alerted South Korean authorities.

The security company Kaspersky Lab said portions of the "WannaCry" ransomware use the same code as malware previously distributed by Lazarus, a group behind the 2014 Sony hack blamed on North Korea.

But it is possible the code was simply copied from the Lazarus malware without any other direct connection.

Another security company, Symantec, has also found similarities between WannaCry and Lazarus tools, but said "they so far only represent weak connections. We are continuing to investigate for stronger connections."

Later Taiwanese state media said the WannaCry cyber attack infected computers in 10 schools, the national power company, a hospital and at least one private business.

However, the Central News Agency said the ransomware program caused no damage to the schools' core database systems.

The news agency said WannaCry also infected computers at an office of the Taiwan Power Company, a hospital and a business in the central city of Taichung. The business, whose name was not given, reported paying 1,000 dollars in bitcoin to unlock files held hostage by the program. It was not clear whether the files had been recovered.

The news agency said there have been no reported incidents of the ransomware affecting government agencies.