Ali Akbar Velayati, a senior adviser to Iran's Supreme Leader Ayatollah Ali Khamenei, confirmed yesterday that a meeting between Turkish, Russian and Iranian leaders on Syria would be held in Tehran.

"Putin said that he will go to Tehran soon to take part in the [Turkey-Iran-Russia] meeting on Syria," the aide was quoted as saying by RT.

Velayeti's remarks were made to Iranian television after his meeting with Russian President Vladimir Putin in Moscow. The trilateral Astana talks on Syria are complementary to U.N.-brokered talks in Geneva to bring an end to the civil war in Syria. Leaders and officials from Turkey, Russia and Iran have held a series of summits in Sochi, Russia to bring together the conflicting parties in Syria, including the moderate opposition and the Syrian regime, excluding groups listed as terrorists by the three countries.

During peace talks in Astana in May 2017, the three guarantor countries agreed to establish de-escalation zones in Idlib and parts of Aleppo, Latakia and Hama provinces. Observation posts will establish, monitor and sustain the current ceasefire in de-escalation zones, deliver humanitarian aid to persons in need and to ensure the secure return of displaced people, the Turkish military previously said. According to the agreement, Turkey is projected to gradually establish 12 observation points, from Idlib's north to south. The last meeting was held in Turkey in April where the parties announced their aim "to rebuild a Syria where peace will prevail."