Paris - Access to several French news sites was blocked on Friday due to a technical problem at their web host that had security experts raising questions about possible Islamist hacking. Over 20 000 French web sites have been attacked by what cyber-security experts for the French military said were "well known Islamist hackers" who became active following the 7 January jihadist strike on French satirical paper Charlie Hebdo that left 12 people dead. The sites for news media 20 Minutes, L'Express, Mediapart, France Info, France Inter, Le Parisien, Slate, ZDNet and Marianne went down at 10:00 (08:00 GMT) on Friday, with some coming back on line after about an hour and a half. Contacted by AFP, web host Oxalide said it would not comment on the cause of the access blockage until it had fully restored operations and confirmed the exact reason for the outage.Emmanuel Parody, editorial director of the CUP Interactive group affected by the incident told AFP that Oxalide had informed him it "initially viewed [the blockage] as a probably a hacker attack, but by the end of the morning considered a technical breakdown equally feasible". Some online security experts think suspect hackers were behind the outage, especially after groups behind the earlier strikes had promised a burst of activity for 15 January that didn't materialise."All the technical characteristics of an access denial attack" were in evidence in Friday's outage, noted Thierry Karsenti, European technical director for online security company Checkpoint.