In his first television appearance since claiming asylum in Russia,
Snowden -- who caused shockwaves around the world by revealing mass US
electronic surveillance programmes -- will give a staunch defence of
privacy in the short pre-recorded broadcast.
"Together we can find a better balance, end mass surveillance and remind the government that if it really wants to know how we feel asking is always cheaper than spying," he says in extracts released by Channel 4.
"The types of collection in the book -- microphones and video cameras, TVs that watch us -- are nothing compared to what we have available today.