Cyber attacks on the Government, the public and industry are at "disturbing" levels, according to the director of Britain's biggest intelligence agency.
Iain Lobham, of the Government's listening centre, GCHQ, warned that the "UK's continued economic wellbeing" was under threat.
Writing in the Times, he said sensitive data on government computers had been targeted, along with defence, technology and engineering firms' designs.
He revealed there had been "one significant (but unsuccessful) attempt on the Foreign Office and other Government departments this summer".
Mr Lobham's article comes ahead of a London conference on cyber-security, which aims to bring together political leaders and technology experts.
Foreign Secretary William Hague told the newspaper there was an "exponential rise" in incidents, with systems such as welfare and tax databases "liable to attack".
"Countries that cannot maintain cyber security of their banking system, of the intellectual property of their companies, will be at a serious disadvantage in the world," Mr Hague added.
Mr Lobham called for an inclusive approach, adding: "We are witnessing the development of a global criminal market place - a parallel black economy where cyber dollars are traded in exchanged for UK citizens' credit card details."