Diplomats from Turkey, the United Nations, Russia and Iran will meet in Geneva in October for the Syrian constitutional committee, Russia's Special Envoy to Syria Alexander Lavrentiev said Tuesday.

"We have agreed on the balance that will be in the lists established by the regime and opposition. We will present the lists to the UN Special Envoy to Syria Staffan de Mistura's approval after we finish our work on them as the three guarantor countries Turkey, Russia and Iran," Lavrentiev said regarding the constitutional committee.

According to an anonymous source that spoke to Anadolu Agency (AA), the group will consist of experts from the three guarantor countries to facilitate the negotiations under the auspices of the United Nations.

On Tuesday, the Turkish Foreign Ministry said an agreement in principle regarding the lists that were proposed by the Syrian regime and opposition, was discussed.

"During the meeting, they discussed the formation of a constitutional committee and its codes of practice which constitute an important step in the struggle of finding a political solution to the Syrian crisis," the ministry said.

Mistura will meet on Friday with officials from Egypt, France, Germany, Jordan, Saudi Arabia, the U.K. and the United States.

On Sept. 18, he will address the U.N. Security Council on the two-day talks. The Geneva meetings held under the U.N. umbrella to end the 7-year-old civil war in Syria consist of four headings including transition, constitution, elections and the fight against terrorism.