A series of cyber attacks that saw 72 organisations across the globe affected has been uncovered by McAfee.

The security firm first discovered the series of attacks, which is thought to be the biggest ever, in March after its research uncovered a number of attack logs while investigating a 'command and control' server obtained in 2009 under an investigation of security breaches at defence companies.

The attacks, which McAfee called 'Operation Shady RAT (Remote Access Tool)' were carried out over a five-year period from 2006 and saw the US, Vietnamese and Canadian governments targeted along with the UN, the International Olympic Committee (IOC) and the World Anti-Doping Agency.

McAfee said that in the case of the UN, hackers infiltrated the UN Secretariat computer system and remained there unnoticed for two years, while trawling through secret data.

An unnamed Asian Olympic Committee was the victim of the longest attack which lasted 28 months, the security firm revealed.

"Even we were surprised by the enormous diversity of the victim organisations and were taken aback by the audacity of the perpetrators," Dmitri Alperovitch, vice president of threat research at McAfee, said in a report about the attacks.

"What is happening to all this data ... is still largely an open question. However, if even a fraction of it is used to build better competing products or beat a competitor at a key negotiation (due to having stolen the other team's playbook), the loss represents a massive economic threat."

McAfee said all of the organisations that had been targeted had been notified and one "state actor" was behind the attacks, although the security firm would not not identify who it was. However, Jim Lewis a cyber expert with the Centre for Strategic and International Studies, was briefed on the discovery by McAfee, told Reuters it was "very likely" China was behind the campaign, especially since the IOC and several national Olympic Committees were attacked in the run-up to the 2008 Beijing Games

"Everything points to China. It could be the Russians, but there is more that points to China than Russia."