'Cyberjack' warning.

TWELVE million computers have reportedly been hijacked by cyber-criminals and detected by security vendor McAfee since January, the firm has said.

It reports there has been a 50% increase in the number of detected so-called "zombie" computers since 2008.

The true number of newly hijacked PCs is likely to be higher than those detected by McAfee alone.

The figures come as a report from Deloitte said a global approach to cyber-security is needed.

"Doing nothing is not an option," said Deloitte's Greg Pellegrino.

Everything that depends on cyberspace faces unprecedented risks said Deloitte Touche Tohmatsu (DTT).

"This issue is moving so quickly, and with so much at stake economically and in terms of safety and security for people, we don't have 100 years to figure this out," explained Mr Pellegrino who is a global public sector industry leader at DTT.

McAfee also revealed that the United States now hosts the world's largest percentage of infected computers at 18% with China a not too distant second with just over 13%.

"The massive expansion of these botnets provides cybercriminals with the infrastructure they need to flood the web with malware," said Jeff Green, senior vice president of McAfee.

"Essentially, this is cybercrime enablement." The DTT findings revealed a growing awareness of the role the internet plays in so many different aspects of our lives from security to commerce and from transportation to communication..