Prime Minister Recep Tayyip Erdogan of Turkey is critical of the UN Security Council for being ineffective in dealing with the conflict in Syria.
He says the Council is repeating mistakes that led to massacres in Bosnia in the 1990s.
The Security Council is divided between Western powers on one side and Russia and China on the other.
"If we leave the issue to the vote of one or two members of the permanent five at the United Nations Security Council, then the aftermath of Syria would be very hazardous and humanity will write it down in history with unforgettable remarks," Mr Erdogan said on Saturday.
"It's high time to consider a structural change for international institutions, especially for the UN Security Council.
"By failing to implement an effective policy towards events in Syria, the Security Council is rapidly losing its legitimacy in the eyes of the oppressed elsewhere in the world," Mr Erdogan said.
He told a conference in Istanbul that reform of the security council should take into account the growing strength of countries such as Turkey, Brazil, India and Indonesia.
"The West is no longer the only centre of the world," he added.