Video footage of a faked chemical attack in Syria, which the Russian military claimed would be "handed to global news outlets by the end of Tuesday", has so far failed to materialise.

According to a briefing note issued by the Russian Centre for Reconciliation of Opposing Sides in Syria and posted on the Russian defence ministry's website, "some Middle East TV-channels and a regional branch of a leading US news channel" (none of them named) had been filming in Jisr al-Shughur, a town in Idlib province currently held by anti-Assad fighters.

The briefing note said:

According to the scenario of the staged scene, civilians of Jisr al-Shughur "were provided with help" by "activists" of "civil defence" (the White Helmets) after an alleged chemical attack carried out by Syrian army using barrel bombs armed with chemical agents.

To make shooting more natural and to ensure rapid collection of soil samples by the White Helmets, early in the morning the[y] delivered two containers with chemical substances based on chlorine from Khirbat al-Jawziyah to Jisr al-Shughur.

The Russian propaganda channel, RT, said the film would be delivered to TV newsrooms for broadcasting after first being posted on social media. The film, it said, was "meant to serve as proof that the Syrian government has conducted a chemical weapons attack in Idlib".

Russia has long claimed that chemical attacks reported in Syria (and in some cases confirmed by OPCW investigators) either didn't happen or were false flag operations by rebels. More recently, however, it has adopted a new tactic of claiming to know about fake attacks that are supposedly in preparation. Up to now, all these predictions have proved wrong, though that doesn't seem to deter the Russians and other supporters of the Assad regime from making them:

February 13: Russian Centre for Reconciliation of Opposing Sides in Syria says it received a phone call from a resident of Saraqeb in Idlib province about plans for a staged attack: "According to the source, on the afternoon of February 12, rebels from the Jabhat Al-Nusra (Al-Nusra Front) terrorist organisation brought three cars packed with more than 20 cylinders of chlorine along with personal protective equipment to Serakab. Additionally, according to the caller, representatives of the local branch of the White Helmets, wearing individual means of protection, conducted rehearsals of 'giving first aid' to 'local residents' who were supposedly suffering from poisoning."

June 23: Sputnik News says Syrian field sources are "monitoring the movement of White Helmets members in the town of Basr al-Harir and other regions in eastern Deraa". The sources said this might signify preparations for a false flag chemical attack but "the tightness of the frontlines in the area may hinder the White Helmets from going ahead with their plans".

August 8: Citing Syrian foreign minister Walid Muallem, Sputnik News says the White Helmets organisation has "kidnapped 44 children in Idlib to use in a staged chemical attack".

August 27: Russian embassy in South Africa tweets: "English-speaking 'foreign specialists' have arrived in Syria to attempt staging chlorine chemical attack early this week. Latest intel indicates the hoax is planned to take place in the village of Kafr Zita (Hama province)." The tweet is accompanied by a photo which appears to show filming of a staged attack, though it was actually taken on the set of "Revolution Man" – a fictional film made by the Syrian government.

August 28: Russian defense ministry says the chemicals intended for use in a fake attack in Idlib "have been already delivered to terrorists in the area with the assistance of the infamous White Helmets group."

August 31: Russian foreign minister Sergei Lavrov says there is "no doubt" that militants are plotting a false-flag chemical-weapons attack in Idlib province, and Russia has "presented concrete facts" about this to both the UN and OPCW.

August 31: Vanessa Beeley, a prominent defender of the Assad regime on social media, tweets: "White Helmets transported drums carrying toxic materials to Saint Nicholas church & National Hospital – Jisr al-Shughour. Location of chemical hoax changed by foreign orders after 1st area exposed. Now Maarrat Al Nu'man is new location." Beeley adds: "Sources on the ground told @khalediskef that the plan is to use 'female' White Helmets for maximum propganda impact."

September 5: Fares Shehabi, a Syrian member of parliament, tweets: "Expect a new WhiteHelmets chemical hoax ahead of the upcoming [UN security council] meeting on Friday to put pressure on Syria. More likely it will take place in Jisr Al-Shugur town as local sources told us."

September 6: Following a meeting with President Assad during a visit to Syria, Republican US state senator Richard Black claims Britain is involved in planning fake attacks: "We knew about four weeks ago that British intelligence was planning to work to stage a false flag chemical attack to pretend that it was the fault of Syria and to blame it on Syria and then to come to the rescue of al-Qaeda."