Britain's Foreign Office and other government departments were targeted for "significant but unsuccessful" cyber attacks earlier this year, the country's spy chief said on Monday.
The UK's "continued economic wellbeing" was under threat because of a "disturbing" number of such attacks on the government, industry and members of the public, warned Iain Lobban, the director of communications intelligence agency GCHQ.
Writing in the Times, he said sensitive data on government computers had been targeted, along with defence, technology and engineering firms' designs.
"I can attest to attempts to steal British ideas and designs - in the IT, technology, defence, engineering and energy sectors, as well as other industries - to gain commercial advantage or to profit from secret knowledge of contractual arrangements," Loban wrote.
He added: "Such intellectual property theft doesn't just cost the companies concerned. It represents an attack on the UK's continued economic wellbeing.
We are also aware of similar techniques being employed to try to acquire sensitive information from British government computer systems, including one significant (but unsuccessful)
According to him, criminals were using cyberspace to extort money and steal identities, as well as exploit the vulnerable.
"We are witnessing the development of a global criminal market place - a parallel black economy where cyber dollars are traded in exchange for UK citizens' credit card details.
Tackling cyber crime matters and it is a very real threat to our prosperity," Loban wrote.
A major cyber security conference is scheduled to be held here from tomorrow. It will be attended by Hillary Clinton, the US secretary of state, and Jimmy Wales, co-founder of Wikipedia, among others.
Foreign Secretary William Hague told the Times: "Countries that cannot maintain cybersecurity of their banking system, of the intellectual property of their companies, will be at a serious disadvantage in the world."