TEHRAN, Young Journalists Club (YJC) - The accusation, made by US Ambassador to the Organization for the Prohibition of Chemical Weapons (OPCW) Kenneth Ward Thursday, came amid Washington ratcheting up pressure on Iran which is refusing to submit to American demands.
Ward did not say Iran has used chemical weapons but rather that it has allegedly maintained facilities and equipment which can be used for their production.
Zarif dismissed the allegations late Friday, saying the US "wants to resort to international conventions to make allegations against Iran when it's made a policy of violating them itself."
Such allegations "by a country that supported Iraq's use of CW [chemical weapons] against Iran, then invaded Iraq to allegedly rid it of them is not just obscene, it's dangerous," he said in a tweet.
Many Iranians are still suffering from the effects of chemical weapons used by former Iraqi dictator Saddam Hussein, who was backed by the US and Europe during his eight-year war on Iran in the 1980s.
At the time, repeated use of chemical weapons by Saddam against Iranian troops and civilians was met with the deafening silence of the West.
The Saddam regime reportedly acquired the technology and material to develop chemical weapons from the US and a number of Western countries, including the Netherlands and Germany.
Classified documents revealed in recent years have showed that the CIA knew about Iraq’s use of chemical weapons as early as 1983, but took no action and even failed to alert the UN.
Iran never retaliated against Iraq’s chemical weapons attacks on troops and civilians, which killed 20,000 Iranians and severely injured 100,000 more.
At The Hague on Thursday, Ward said Washington "is also concerned that Iran is pursuing central nervous system-acting chemicals for offensive purposes."
"The United States has had longstanding concerns that Iran maintains a chemical-weapons program that it failed to declare to the OPCW," he said.
Ward cited the discovery of chemical-filled artillery projectiles, mortars, and aerial bombs in Libya of what he claimed Iranian origin as proof that Tehran did not fully disclose its capabilities.
The Iranian Foreign Ministry said it "strongly rejects the groundless" accusations. "The United States...has made, as is its habit, baseless accusations against the Islamic republic which we strongly reject," it said in a statement.
Iran's former ambassador to the International Atomic Energy Agency Reza Najafi said Tehran is not surprised by the "baseless" US accusations.
"We should not forget that the US is the only signatory to the Chemical Weapons Convention that possesses [chemical] arms and has not yet completed the annihilation of its stockpile of chemical weapons," he said.
"The loyal ally of the US in the Middle East, namely the Israeli regime, has also developed its chemical weapons with Washington's help; that is another example of America's non-compliance," he added.