MI5 is working to counter "astonishing" levels of cyber-attacks on UK industry, the organisation's chief has said.
In his first public speech for two years, Jonathan Evans warned internet "vulnerabilities" were being exploited by criminals as well as states.
The attacks were a threat to the integrity of information, he added.
Mr Evans also warned the London 2012 Olympics was an "attractive target" for terrorist groups, but said security preparations were well under way.
