Iranian President Hassan Rohani has publicly acknowledged for the first time that chemical weapons killed and injured people in Syria.
Iranian news agencies on August 24 quoted Rohani as saying Tehran "completely and strongly" condemned the use of chemical weapons.
Rohani, however, did not say who had used the weapons.
Iran's Foreign Ministry has said that if such attacks were proved, the rebels would be responsible.
Iran is a major ally of the Syrian government.
Syrian opposition sources have estimated that between 500 and 1,300 people died in the alleged gas attack near Damascus on August 21.
They blamed the government for the attack.
The government denies using chemical weapons.
Iranian news agencies on August 24 quoted Rohani as saying Tehran "completely and strongly" condemned the use of chemical weapons.
Rohani, however, did not say who had used the weapons.
Iran's Foreign Ministry has said that if such attacks were proved, the rebels would be responsible.
Iran is a major ally of the Syrian government.
Syrian opposition sources have estimated that between 500 and 1,300 people died in the alleged gas attack near Damascus on August 21.
They blamed the government for the attack.
The government denies using chemical weapons.