Leaders from more than 50 Muslim nations accused Iran on Friday of supporting terrorism and interfering in the internal affairs of regional states including Syria and Yemen.

The leaders have been attending a summit in Istanbul this week of the 57-member Organisation of Islamic Cooperation (OIC) to discuss a range of issues such as the humanitarian fall-out from Syria's civil war.

"The Conference deplored Iran's interference in the internal affairs of the States of the region and other Member States including Bahrain, Yemen, Syria, and Somalia, and its continued support for terrorism," the OIC said in its final summit communique.

It also stressed the need for "cooperative relations" between Iran and other Muslim countries, including refraining from the use or threat of force.

Both Turkey, which has assumed the three-year rotating presidency of the OIC, and Saudi Arabia are part of the U.S.-led coalition against Islamic State militants in Syria and are also opponents of President Bashar al-Assad, a stance that has put them at odds with Iran, an ally of the Syrian leader.

Iran is also allied with the Houthi movement in Yemen, which has been battling forces loyal to Yemen's president.