Political Correspondent
Updated: 06:42, Thursday June 07, 2007

Police and intelligence agencies fear terrorists could be using new ways of communicating over the internet that are virtually impossible to trace and intercept, Sky News has learned.

VOIP calls are impossible to tap

Companies like Skype are at the forefront of one of the fastest growing sectors of the internet - VOIP or Voice Over Internet Protocol, which allows people to talk via their computers.

Although the intelligence community can tap into regular phone conversations, whether on landlines or mobiles, VOIP communications pass under the radar.