This summer's London Olympics "will not be immune" to cyber attacks by those seeking to disrupt the Games, a Cabinet minister warned today.

Cabinet Office minister Francis Maude issued the caution as he revealed that UK Government computer networks are "regularly targeted" by foreign intelligence agencies and groups working on their behalf.

Speaking during a visit to Estonia, Mr Maude said the UK was aware of the dangers from "the dark side of cyberspace", citing last year's launch of the National Cyber Security Programme and the decision to rate electronic attacks a tier one UKthreat to national security, with £650 million allocated over four years to fund a response.

A dedicated unit is helping to guard the London Games against cyber-attack, he confirmed.

And he announced that £400,000 was being committed this year to expanding the Get Safe Online campaign providing education, information and advice on internet safety.

Online offences including identity theft, phishing scams and card fraud were "some of the fastest-growing crimes in the UK", said Mr Maude, who has departmental responsibility for the Office for Cyber Security.

"A recent survey showed that one in seven large organisations have been hacked in the last year, with large organisations facing one outsider attack per week; small businesses face one a month," he said.

"Intellectual property theft through cyber crime is a major concern.

"Countries and organisations across the globe are losing billions of pounds each year to cyber criminals.

"UK Government networks continue to be regularly targeted by foreign intelligence agencies, or groups working on their behalf.

"And we know that the threat is accelerating.

"High-end cyber security 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 cyber criminals 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."

He added: "This year's Olympics in the United Kingdom will not be immune to cyber attacks by those who would seek to disrupt the Games.

"The Beijing Olympics saw 12 million cyber security incidents during their Olympics.

"We have rightly been preparing for some time - a dedicated unit will help guard the London Olympics against cyber attack - we are determined to have a safe and secure Games."

Despite awareness of the threat, Mr Maude insisted that the Government would "resist the temptation to over-regulate and control" the internet, which generates around 6% of UK GDP, with £3 in e-commerce exports for every £1 in imports.

"We're not trying to protect ourselves from the internet, which remains a massive force for good in the world," he said.

"We need to protect the internet from hostile actors - the criminals, the hackers, the terrorists - who want to exploit it for less positive ends.

"And as we meet the challenges presented by cyberspace, and shape its future, governments need to resist the temptation to over regulate and control. The internet after all has flourished precisely because it has been shaped by its users, not by governments."

Mr Maude was speaking to the International Centre for Defence Studies in Estonia, which is rated one of the most connected countries in the world and a pioneer in cyber security.

During a three-day visit, he was also touring the Nato Cyber Defence Centre of Excellence and meeting President Toomas Hendrik Ilves and Prime Minister Andrus Ansip.