Terrorist organisations such as Al-Qaeda are gradually increasing their presence in social media platforms such as YouTube, Twitter, Facebook and Instagram, a new report has found.

A study from the Woodrow Wilson Center Commons Lab in Washington warned that this usage could pose a big challenge for security agencies across the world.

University of Haifa professor of communications and author of the report Gabriel Weimann said terrorists have long used the Internet for purposes that range from recruitment, propaganda, and incitement to data mining and fundraising.

"They have turned to the new media not only because counterterrorism agencies have disrupted their traditional online presence but also because the new media offers huge audiences and ease of use," he said, highlighting video-sharing website YouTube as a particularly important platform.

"Terrorist followers, sympathizers, converts, and newcomers also find in the new media a much lower threshold to access terrorist-produced and terrorism-related content than they faced in discovering and signing up for access to the hardcore forums (those which have not been shut down, at least)."

Weimann said that in 1998, there were only 12 terrorist-related websites in existence, but over the years this number has ballooned to now total more than 10,000.