Terrorists are using social media, such as Facebook, Twitter and YouTube, to spread propaganda, recruit sympathisers and plot potential attacks, according to a United Nations’ report.

The report, entitled ‘The Use of the Internet for Terrorist Purposes’, said that the promotion of extremist rhetoric encouraging violent acts is also a common trend across the growing range of Internet-based platforms that host user-generated content.

According to the report, content that might formerly have been distributed to a relatively limited audience, in person or via physical media, such as compact discs (CDs) and digital video discs (DVDs), has increasingly migrated to the Internet.

The report also cited the case of Adlene Hicheur, an Algerian-born French national, who was imprisoned in May this year for his role in an al-Qaeda terror plot.

The United Nations Office on Drugs and Crime (UNODC) executive director Yury Fedotov said potential terrorists use advanced communications technology often involving the Internet to reach a worldwide audience with relative anonymity and at a low cost.

"Just as Internet use among regular, lawful citizens has increased in the past few years, terrorist organizations also make extensive use of this indispensable global network for many different purposes," Fedotov said.

Recently, US defence secretary Leon Panetta has warned that the cyber attckers are developing the ability to strike the country’s power grids, financial systems and government systems.