Claims that Iran is arming and training Syrian forces in support of President Assad's crackdown on the anti-government uprising have been denied by Tehran.
Iran has signalled it is making steps towards a U-turn in its support of Assad after softening its tone and apparently indicating a degree of backing for the protesters.
Iranian President Mahmoud Ahmadinejad's initial support for President Assad's brutal attempts to quash the uprising has waned as the tide has shifted against the Syrian leader.
French media also reported that Iranian representatives had met Syrian opposition leaders in Europe this week. The meetings are the clearest indication that the Iranians are preparing for a post-Assad scenario.
Mr Ahmadinejad has spoken in recent weeks of the protesters' "legitimate demands" and called on President Assad to "respect people's right to elect leaders and achieve freedom".
Amnesty International published a report on Wednesday claiming that around 90 detainees had been killed in Syria during the five-month uprising.
It detailed dozens of cases where victims' bodies showed signs of having been tortured before death. Some of the victims were no older than 13. Amnesty said it believed the Assad regime to be "systematically persecuting its own people on a vast scale".