Cyber attack threat to London 2012 Olympics revealed by security chiefs

Fears that a cyber attack could have turned off the lights during the opening ceremony of the London 2012 Olympics have been detailed by the security services for the first time.

Oliver Hoare, head of Olympic cyber security, told BBC Radio 4 he was woken at 04.45 on the morning of the opening ceremony by a call from GCHQ warning of a "credible attack" on the electricity infrastructure supporting the Games.

"There was a suggestion that there was a credible attack on the electricity infrastructure supporting the Games," said Hoare.

Although terrorism had topped the list of concerns regarding the opening ceremony, extensive precautions against this kind of attack had been put in place.

"We'd tested no less than five times the possibility of an attack, a cyber-attack, on the electricity infrastructure," Hoare said.

The call from GCHQ turned out to be a false alarm. However, Sir Iain Lobban, the head of GCHQ, told the BBC that such an attack remains a "realistic threat".

His intelligence agency is working with partners to protect Britain's national infrastructure, including the national grid, from such an attack, he said.

"We have seen technical reconnaissance of parts of our critical national infrastructure ... Not to such an extent that we would raise a red flag but certainly we've seen an interest, an intentional interest, in parts of that infrastructure," Lobban said.

The revelations come just one week after Lobban told BBC Radio 4 that UK Government and industry networks are subjected to 70 cyber espionage operations per month.