Nearly eight out of 10 companies rate security as the single most important attribute of corporate networks, according to new research.

A poll of 254 senior executives by the Economist Intelligence Unit found that security has replaced network reliability and availability as the most critical network attribute.

But while businesses worry about security, the vast majority of executives want to further open up their networks to partners, customers and mobile workers. This creates friction between general management and IT executives, who point out that opening up the network can increase vulnerability.

More than 80 per cent of all the executives surveyed believe that their goals of giving remote workers access to corporate networks and improving the availability of customer data for employees will leave their firms vulnerable to security threats.

Security spending itself is likely to shift focus over the next few years, according to the study, moving from layers of perimeter protection and intrusion detection to better tools aimed at preventing attacks.

The report also noted that the spiralling threat of cyber-attacks and increased vulnerabilities are pushing up costs, causing network security spending to outpace overall IT expenditure.

On average, the firms surveyed devoted nine per cent of the IT budget to network security in 2002. This figure rose to 11 per cent last year and is expected to reach 13 per cent this year.

"In a global networked economy of internet connectivity and interoperability, isolation leads to irrelevance for enterprises that can't protect their networks," said Hossein Eslambolchi, president of AT&T global networking technology services, which sponsored the survey, in a statement.

Increasingly, the chief executive is taking ownership of network security policy in some companies, the report found, while in others a relatively new role, that of chief security officer, is emerging.