The London Olympics "will not be immune" to cyber-attack, Cabinet Office Minister Francis Maude has warned.
He said attackers "would seek to disrupt the Games", noting that the Beijing Olympics saw 12 million cybersecurity incidents in 2008.
"We have rightly been preparing for some time a dedicated unit which will help guard the London Olympics against cyber-attack," he said.
"We are determined to have a safe and secure Games."
Mr Maude, who is responsible for the UK's Office of Cyber Security, made the comments during a visit to Estonia, a country considered a pioneer in the field.
"UK government networks continue to be regularly targeted by foreign intelligence agencies, or groups working on their behalf," he said.
"And we know that the threat is accelerating."'Fast and flexible'
Mr Maude added: "High-end cybersecurity solutions that were used 18 months ago by a limited number of organisations to protect their networks may already be out in the open marketplace - giving cybercriminals the knowledge to get round these protective measures.
"Our responses have to be fast and flexible. What works one day is unlikely to work a matter of months or even weeks later."
Last year, the government announced a dedicated team charged with protecting this summer's Games from cyber-attack.
A series of worst-case scenarios is being tested on the computer systems throughout this month - although Olympics bosses have said they are unaware of any specific threat.
Mr Maude said that despite the risks, the government would "resist the temptation to over-regulate and control" the internet.
Last month saw the government heavily criticised over plans to extend "snooping" abilities online.
The minister added: "We need to protect the internet from hostile actors - the criminals, the hackers, the terrorists - who want to exploit it for less positive ends."
During his three-day visit, Mr Maude will also visit Nato's Cyber Defence Centre of Excellence.