This was the Liberty ship Harvey disaster in Bari that I was thinking of: it's defeinitely different from the Rowan explosion.
Note that this reference confirms that the Arabs tried to use poison gas warfare AGAISNT the jews in Isreal BEFORE the British gave them the Palestinian mandate after the war!
http://en.wikipedia.org/wiki/Poison_gas#Chemical_warfare_in_World_War_II
On the night of December 2, 1943, German JU-88 bombers attacked the port of Bari in Southern Italy, sinking several American ships - among them John Harvey, which was carrying mustard gas intended for use in retaliation by the Allies if German forces initiated gas warfare. The presence of the gas was highly classified, and authorities ashore had no knowledge of it - which increased the number of fatalities, since physicians, who had no idea that they were dealing with the effects of mustard gas, prescribed treatment proper for those suffering from exposure and immersion.
The whole affair was kept secret at the time and for many years after the war (in the opinion of some, there was a deliberate and systematic cover-up). According to the U.S. military account, "Sixty-nine deaths were attributed in whole or in part to the mustard gas, most of them American merchant seamen" [3] out of 628 mustard gas military casualties[4]. Civilian casualties were not recorded. Part of the confusion and controversy derives from the fact that the German attack was highly destructive and lethal in itself, also apart from the accidental additional effects of the gas (it was nicknamed "The Little Pearl Harbor"), and attribution of the causes of death between the gas and other causes is far from easy. The affair is the subject of two books: Disaster at Bari by Glenn B. Infield and Nightmare in Bari: The World War II Liberty Ship Poison Gas Disaster and Coverup by Gerald Reminick.
Although chemical weapons were not intentionally deployed on a large scale during World War II, there were some recorded uses of them by the Axis Powers, when retaliation was not feared:
The Japanese used mustard gas and the recently-developed blister agent Lewisite against Chinese troops. During these attacks, the Japanese also employed biological warfare by intentionally spreading cholera, dysentery, typhoid, bubonic plague, and anthrax. As of 2005, 60 years after the end of the war, canisters that were abandoned by Japan in their hasty retreat are still being dug up in construction sites, causing many injuries and deaths.
In 1944, the Grand Mufti of Jerusalem, Amin al-Husayni, the senior Islamic religious authority of the Palestinian Arabs and close ally of Adolf Hitler, sponsored an unsuccessful chemical warfare assault on the Jewish community in Palestine. Five parachutists were supplied with maps of Tel Aviv, canisters of a German–manufactured "fine white powder," and instructions from the Mufti to dump chemicals into the Tel Aviv water system. District police commander Fayiz Bey Idrissi later recalled, "The laboratory report stated that each container held enough poison to kill 25,000 people, and there were at least ten containers." [5]
The Nazis used the insecticide Zyklon B, which contains hydrogen cyanide, to kill large numbers of Jews and other victims in concentration camps such as Auschwitz and Majdanek during the Holocaust.