After a UN report concluded that chemical weapons were used in Syria last month, efforts to determine who was to blame rage on via websites.
UK Foreign Secretary William Hague believes the weapons inspectors' findings are "fully consistent" with his belief that Bashar al-Assad's government was responsible. But videos uploaded to the YouTube and LiveLeak websites this week claim to show opposition forces launching the 21 August attack on the Damascus suburb of Ghouta. They were swiftly picked up by media outlets in countries allied to Syria, including state-owned TV channel Russia Today.
The poor-quality videos show men standing around an artillery vehicle, wearing what appear to be gas masks, with the cannon's barrel draped in large black flags bearing Islamic symbols and the name of rebel group Liwa al-Islam. In one video, a man mentions the group and - after one blast - the men chant "Allahu Akbar", or "God is great". Liwa al-Islam eventually released a statement declaring the videos to be "completely fabricated" and blaming the Assad government which, it says, is the only force in Syria in possession of the weapons shown in the video. But only after several days of examination by bloggers.
BBC Monitoring's Mohamed Madi says the videos "look suspicious for several reasons", such as being filmed in almost complete darkness despite there having been a full moon on the night in question. "The videos also contain jihadist paraphernalia which is perhaps a little too obvious, such as the large black flags and constant chanting," he adds. The videos were uploaded onto a new YouTube account - with text suggesting a clear agenda - around the time the weapons inspectors reported, when usually rebel groups upload dozens of videos over several months.
Blogger Eliot Higgins, writing as Brown Moses, is among those attempting to provide objective analysis of the videos - including examination of the weaponry involved - and his posts provoked a debate about whether weapons capable of launching a chemical attack had fallen into rebel hands. He's clearly sceptical about the videos but Russia Today cited his blog when reporting that "a prominent Syria blogger has posted footage allegedly showing chemical weapons being used by radical rebels". Higgins issued a response condemning the channel's use of his blog to "give credence to these dubious videos". But with UN Secretary General Ban Ki-moon indicating the evidence uncovered by weapons inspectors pointed to a war crime, media focus on this sort of video "evidence" looks likely to intensify.