GENEVA (Reuters) - Senior officials from Iran, Russia and Turkey held “substantive” talks on Tuesday on how Syria’s constitutional committee will be set up and will function, and more such talks are planned within weeks, U.N. Syria envoy Staffan de Mistura said.

The discussions in Geneva were the first visible diplomacy in months between countries involved in the Syrian war, and the effort to form a constitutional committee follows two years of futile rounds of talks that never led to direct meetings between the warring sides.

“During the meeting, constructive exchanges and substantive discussions took place on issues relevant to the establishment and functioning of a constitutional committee, and some common ground is beginning to emerge,” de Mistura said in a statement.

De Mistura has a mandate from the U.N. Security Council to forge a political agreement between Syria’s warring sides, including a new constitution and new elections.

A congress of Syrian activists held in the Russian resort of Sochi in January gave him the task of setting up a committee to draft a new constitution. He promised at the time to consult widely on the membership, which would be unlikely to exceed 50.

The government of President Bashar al-Assad has sent the U.N. a list of nominees and Syria’s opposition is expected to follow suit soon.

The meeting brought together the Turkish Foreign Ministry’s Deputy Undersecretary Sedat Onal, Russia’s Syria envoy Alexander Lavrentiev and the Iranian foreign minister’s Special Assistant in Political Affairs Hossein Jaber Ansari.

De Mistura plans to meet senior officials from the United States, Saudi Arabia, Jordan, France, Britain and Germany next week, and expects the Iranian, Russian and Turkish officials to return for more talks in the next few weeks “to widen the common ground”, the statement said.