Internet-based attacks on critical systems such as gas, power and water have increased around the world, a report suggests.

一份报告显示，世界上针对诸如石化、电力和水力等关键系统的网络攻击正在逐渐增多。

Security firm McAfee surveyed 200 IT executives working for utility companies in 14 countries.

Eight out of 10 said their networks had been targeted by hackers¹ during the past year.

China was seen as the most likely source of attacks, followed by Russia and the United States.

The number of reported incidents was higher than in 2009 when just over half of those asked said they had fallen victim.

Denial of service

Most of the reported security breaches² took the form of distributed denial of service (DDOS) attacks.

These typically involve a network of computers, under the control of criminals, overwhelming a company's internet-connected systems.

While such incidents have the potential to impact websites and corporate³ networks, researchers said it was unlikely they were intended to cut off energy supplies.

However, there remained a possibility that DDOS attacks could do more harm in future, according to Stewart Baker⁴, a former US national security advisor⁵ to President George W Bush and one of the report's authors.

"We asked what what the likelihood was of a major attack that causes significant outage.

"That is one that causes severe loss of services for at least 24 hours, loss of life or personal injury or failure of a company.

"Three quarters thought it would happen within the next two years," he said.