Britain has become a target of “disturbing” levels of cyber attacks with an “exponential rise” in attempts to steal sensitive data held on government computer systems, including those of the Ministry of Defence, said the head of the largest intelligence unit on Monday.

Iain Lobban, who runs the Government's Communications Headquarters (GCHQ), warned the situation had become so serious that Britain's “continued economic wellbeing” was under threat.

The disclosure came on the eve of a two-day international conference on cyberspace called by Foreign Secretary William Hague amid allegations that the government had failed to take the cyberwarfare seriously enough.

The London Conference on Cyberspace, to be attended by U.S. Secretary of State Hillary Clinton, the European Union's digital chief, Neelie Kroes, and a host of political leaders and experts from around the world, will discuss ways to formulate a “global coordinated response” to the growing threat to not only government data but also personal information of individuals.

More than 150 websites were reported to be offering illegally obtained information with details of credit card users being traded for less than £1.

Mr. Hague told The Times that a new dividing line had opened up between countries able to protect their citizens, companies and government systems, and those that could not.

“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. It will be harder for businesses to grow and survive and for individuals to maintain their confidential information. That is why it is urgent to prevent this,” he said pointing out that the government had set aside £650 million to prevent cyber attacks over the next four years.

Writing in the same newspaper, Mr. Loban said there was a flourishing “global criminal market place — a parallel black economy where cyber dollars are traded in exchange for U.K. citizen credit card details”.

“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.”

In the past one year, the Ministry of Defence claimed to have foiled more than 1,000 cyber-attacks from alleged criminals and foreign intelligence services. There had also been a “significant” attack on computer systems of the Foreign Office.