Turkey on Friday lashed out at the United Nations for failing to resolve international crises, after Saudi Arabia accused the world body of "double-standards" in ending conflicts, such as the civil war in Syria.

"The United Nations are losing quite a lot of their credibility," Dogan news agency quoted Turkish President Abdullah Gul as telling journalists in Istanbul.

Gul spoke after oil powerhouse Saudi Arabia -- like Turkey a staunch backer of the rebellion against the Iranian-backed regime of Syrian President Bashar al-Assad -- rejected a Security Council seat one day after winning it.

"I understand that Saudi Arabia's decision aims to draw the international community's attention to this situation ... We must respect their decision," said Gul.

The Saudi foreign ministry said on Friday Riyadh would not be member of a body that has been unable to tackle long-standing Middle East conflicts or rid the region of the threat of nuclear war.

Turkish Prime Minister Recep Tayyip Erdogan has repeatedly called for a reform of the 15-member Security Council to give Muslim nations more clout.

In addition to its five permanent members, the Council has 10 seats that are awarded for two-year periods by the General Assembly, which holds a vote every year for five of the seats.

Saudi Arabia was on Thursday chosen along with Chile, Chad, Lithuania and Nigeria.