"I can only say that he is going to Turkey in the beginning of June. It was the SOC [Syrian Opposition Coalition] who invited him and he accepted the invitation. He will be in Istanbul," Jessy Chahine told RIA Novosti.
Another source close to intra-Syrian negotiations told the agency de Mistura's visit to Turkey is planned for later next week.
UN Secretary-General Ban Ki-moon's special envoy has been holding bilateral talks with a wide range of Syrian and international participants in Syrian conflict regulation talks since May 5.
Syria has been engulfed in a civil war with a number of militant groups since 2011, leading to several rounds of reconciliation talks between the government and the opposition.
The latest consultations in Geneva mediated by Mistura and involving the ruling regime, opposition, regional players and the UN Security Council is currently underway, expected to last several weeks.
