An intelligence officer with the Canadian Forces has been arrested for allegedly passing secrets to a foreign entity or terrorist group.

Whistle-blower group WikiLeaks says it has begun publishing more than five million emails from a U.S.-based intelligence company, which the group believes has been targeting WikiLeaks and its founder, Julian Assange.

International groups that have been declared terrorist organizations in the West, such as al-Qaeda, Hamas and Hezbollah, have shifted the focus of their recruitment and intelligence gathering to social networks such as Facebook and Twitter, according to a new study.