Syria tested firing systems for poison gas shells at the country's largest chemical weapons research center at Safira, east of Aleppo, last month, German weekly Der Spiegel reported on Monday, citing statements from various witnesses.
According to the report, Iranian Revolutionary Guard officers were flown in by helicopter to witness the testing.
Several empty shells, designed to carry chemical weapons, were fired by tanks and helicopters in a desert location near the research center, Der Spiegel quoted the witnesses as saying.
According to the report, Syria has reinforced security at the facility and made efforts to safeguard its electricity supply in recent months, in case of rebel attack.
Both the US and Israel have expressed concern over Syria's stockpile of chemical weapons falling into the wrong hands or being used by Syrian President Bashar Assad to quell the uprising in the country.
US President Barack Obama warned last month that any sign that Assad was starting to utilize the weapons, or move them, would constitute a "red line" that could trigger US military intervention in the conflict.
"We cannot have a situation where chemical or biological weapons are falling into the hands of the wrong people," Obama told an impromptu White House news conference. He acknowledged he was not "absolutely confident" the stockpile was secure.
Defense Minister Ehud Barak said in July that Israel would take military action if needed to prevent Syria's chemical weapons from falling into the hands of Hezbollah in Lebanon.
According to Monday's report in Der Spiegel, the Safira chemical weapons research center includes scientists from North Korea and Iran who produce chemical weapons such as mustard gas and sarin which they test on animals.
The German weekly quoted a member of the Free Syrian Army as saying that the rebels are not planning to attack or capture the site.
Reuters contributed to this report.
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