"We condemn chemical weapons," Ali Akbar Salehi told Germany's Der Spiegel newsweekly in an interview published on Sunday.
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Iran, a strong Damascus ally, was itself a victim of chemical warfare during its conflict with Iraq in the 1980s, Salehi recalled.
But when pushed to say whether Iran would abandon its ally in the event that Assad's regime was found to be using the weapons, the minister remained cagey.
Tehran is "categorically against all weapons of mass destruction", he said.
Iran is currently facing criticism over its nuclear program which the West suspects is a front for developing weapons.
Both the Damascus regime and the rebels are suspected of having resorted to chemical weapons but Washington and the UN have said there was no incontrovertible evidence yet.
With fears the war, now in its third year, could turn even deadlier, diplomatic efforts have been ramped up, with Russia and the US last week renewing joint efforts to find a solution to the crisis.
Salehi told Spiegel his country was willing to take part in an international conference on Syria proposed by the US and Russia, which could take place later this month.
Iran could "launch talks between Syria's government and opposition", he said, marking a step towards greater involvement for Iran which has until now called only for talks between Syria rebels and the regime to form a transition government.
Salehi said he was "confident" that progress was being made in the conflict, which is estimated to have killed 70,000 and displaced millions more internally and in neighboring countries.
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