Iranian Foreign Minister "Mohammad Javad Zarif" said there is "good coordination" between Syria and its main allies, Moscow and Tehran, ahead of next week's planned peace conference.
His comments came as the three countries' foreign ministers huddled in Moscow Thursday to devise a joint stance in Switzerland peace talks after months of delays.
"There is good coordination among Moscow, Tehran and Damascus for an active and constructive presence at Geneva-2", state broadcaster IRIB's website quoted Zarif as saying.
Ahead of the talks, Russian Foreign Minister "Sergei Lavrov" said Moscow and its allies had nothing to hide.
"We have nothing to hide. We have no hidden agenda," he said, before he and Zarif joined Syrian Foreign Minister "Walid Muallem" for more discussions.
With Geneva-2 conference set to open on Wednesday, Moscow wants to convince Washington to accept Tehran's presence at the talks .
The United States says Iran must accept a political transition in Syria before it can formally join the talks, and U.N Secretary General "Ban Ki-moon" has said no final decision had been reached on the Islamic republic's involvement.
But Zarif said Iran would only attend "without preconditions".
It remains unclear whether Syria's divided opposition, which is strongly opposed to any Iranian participation in the talks, will even attend the conference.
Zarif also warned about the spillover of the Syrian war into neighbouring countries, stressing that "extremism has spilled over from the Syrian borders and now is threatening regional countries such as Lebanon, Iraq, Jordan and Saudi Arabia".