Most likely must have been some kind of speculative FAE weapon, described in Wikipedia article on Thermobaric weapons
A fuel–air explosive (FAE) device consists of a container of fuel and
two separate explosive charges. After the munition is dropped or
fired, the first explosive charge bursts open the container at a
predetermined height and disperses the fuel (also possibly ionizing
it, depending on whether a fused quartz dispersal charge container was
employed) in a cloud that mixes with atmospheric oxygen (the size of
the cloud varies with the size of the munition). The cloud of fuel
flows around objects and into structures. The second charge then
detonates the cloud, creating a massive blast wave.
There was this segment in an old pbs.org article
NARRATOR: In Germany, prosecutors are now investigating the aerospace
giant Messerschmitt, Bolkow and Blohm for its involvement in Iraq's
major missile program. Investigators are focusing on allegations that
MBB, which developed NATO warheads, supplied warhead technology to the
Iraqis, including an advanced and particularly lethal version called a
DAVID SAW, Military Technology Magazine: Fuel-air explosives are an
extremely nasty and devastating weapon. When they are ignited, it
creates a fireball and pressure effect that, in American tests, has
been proven to be five times greater than TNT.
What's speculative is that I have not found anything about such weapons being used to deliver a toxic gas. These are explosives after all. If that's what the media actually stated then could be they got it garbled up or speculated on purpose.