The increasingly complex IT environment means that many existing cyber-defences are no longer fit for purpose.

The warning comes from Joel Bagnal, executive vice president of US government operations at Detica, and a former US Deputy Assistant for Homeland Security.

Bagnal said during his speech at the Information Assurance 08 Conference in London that all organisations need new ways of managing the growing risks and threats to national and international cyber-security.

"The growth of cyber-space, and the explosion of data volumes created by the internet and global telecoms networks, have created a highly complex environment," he said.

"This presents a significant security challenge for governments because criminals from minor offenders to international terrorists can now threaten individual well-being and national security in ways that were simply not possible in the past."

Bagnal believes that cyber-space gives criminals the capability to conduct illegal activities on a vast scale and in a very dynamic way.

"Our cyber-security defences are, in many cases, no longer adequate in today's environment, making us potentially vulnerable to sophisticated attacks, " he said.

Only by combining resources from every facet of society, including government, private organisations, local authorities and individuals, can the threat of hackers and cyber-warfare be effectively addressed.

Information Assurance 08 aims to bring together everyone in government who plays a critical role in information security to discuss the ways information is used, shared, stored and protected.