Paris (AFP) - After having used the Internet profusely for propaganda and recruitment, jihadist organisations have realised that investigators are gleaning crucial information online and are increasingly concealing their web presence, experts say.Apart from recent orders given to fighters to limit their exposure, erase the footprint of their online activity and avoid revealing too many place names or faces, the Islamic State and Al-Nusra Front groups are increasingly using the "Dark Web" -- the hidden part of the Internet protected by powerful encryption softwares."Sometimes we get the geographical location of some fighters thanks to Facebook," Philippe Chadrys, in charge of the fight against terrorism at France's judicial police, said earlier this week."Some even publish it on the public part of their account.