Posters of U.S. dollar and Turkish lira are seen on a currency exchange shop in the city of Azaz, Syria, on Aug. 18, 2018. (Reuters file photo)

ISTANBUL, Nov. 28 (Xinhua) -- Turkish President Recep Tayyip Erdogan on Wednesday called on the Islamic world to use national currencies in trade so as to be free from "imperialist shackles."

"There is no other way out other than using national currencies in trade among the Islamic countries," Erdogan said at a meeting of the Organisation of Islamic Cooperation (OIC) in Istanbul.

"Otherwise we will continue to be crushed under the dollar exchange rate," he added.

The Turkish leader also urged the Islamic countries to complete the necessary procedures to make preferential trade system "a reality" to increase their internal trade to 25 percent.

"The more we invest in each other as member countries, the stronger we will be," Erdogan told the 34th ministerial session of the OIC's Standing Committee for Economic and Commercial Cooperation.

He advised OIC member states to modernize and simplify their custom systems to better cope with the trade wars across the globe.

The OIC is the second largest inter-governmental organization after the United Nations, with 57 member states spread over four continents.