A Syrian military installation rocked by an explosion in July was being used to develop chemical weapons, and Iranian engineers were among those killed, a respected defense publication reported Wednesday.

Jane's Defence Weekly said the blast hit the site of a joint Iranian/Syrian project to fit short-range ballistic missiles with chemical warheads.

The July 26 explosion struck a military complex outside the city of Aleppo, killing at least 15 soldiers and wounding 50 others, according to Syria's state news agency, SANA. The agency said the blast was caused when high summer temperatures set off high-explosive materials at a weapons depot.

But Jane's cited Syrian defense sources as saying the explosion took place during a test to fit a "Scud C" missile with a mustard-gas warhead. It quoted the sources as saying the explosion occurred when fuel caught fire in the missile production laboratory.

"The blast dispersed chemical agents (including VX and Sarin nerve agents and mustard blister agent) across the storage facility and outside," the publication quoted the sources as saying.

The magazine said that, in addition to the 15 Syrian troops, "dozens" of Iranian weapons engineers were killed.

Jane's, based in southern England, said the chemical weapons program was part of a strategic co-operation accord signed between Syria and Iran in November 2005.

The magazine quoted Syrian opposition sources as backing up the claim that Iranians were at the site. They said vehicles destined for car-bomb attacks in Iraq were prepared at the same military camp under the supervision of the Iranian Islamic Revolutionary Guard Corps and the Syrian intelligence services.