Saudi Arabia rejected membership of the UN Security Council on Friday, a day after it was elected to the body, accusing it of "double-standards" in resolving world conflicts, namely Syria.
One analyst said the move also reflects Riyadh's disappointment with the diplomatic opening between ally Washington and archfoe Iran, which it accuses of interfering in regional states.
"Work mechanisms and double-standards on the Security Council prevent it from carrying out its duties and assuming its responsibilities in keeping world peace," the foreign ministry said.
"Therefore Saudi Arabia... has no other option but to turn down Security Council membership until it is reformed and given the means to accomplish its duties and assume its responsiblities in preserving the world's peace and security," the statement said.
Oil powerhouse Saudi Arabia -- a staunch backer of the rebellion against the Iranian-backed regime of Syrian President Bashar al-Assad -- won the seat Thursday for the first time ever.
Saudi UN Ambassador Abdullah al-Mouallimi welcomed the election as a reflection of Riyadh's "long-standing policy in support of moderation and in support of resolving disputes in peaceful means."
But the foreign ministry on Friday said 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.
Saudi analyst Abdulaziz Sager, who heads the Gulf Research Centre, said Saudi Arabia wanted to send the world two messages.
"First it wanted to show that it is a power to be reckoned with (by securing 176 votes in the 193-member General Assembly). And then it decided to act from a position of strength.
By declining the seat it is expressing its "indignation" with the veto-wielding five permanent members of the council and its "displeasure" with US policies in the region, mainly Iran.
The United States, a Saudi ally, is one of the five permanent members of the council along with Russia, France, Britain and China. It has recently opened up diplomatically to Riyadh's arch-foe Iran.
"Saudi Arabia believes Iran is interfering in Syria, Iraq, Yemen and Bahrain.. and that the United States is willing to let Iran play a role in the region," Sager added.
The foreign ministry statement pointed specifically to the nearly three-year civil war in Syria and the protracted Palestinian-Israeli conflict, as key reasons to decline a council seat.
"Failing to find a solution to the Palestinian cause for 65 years" it said, has led to "numerous wars that have threatened world peace."
Likewise, it said, "allowing the regime in Syria to kill its own people with chemical weapons... without confronting it or imposing any deterrent sanctions... is a proof of the inability of the Security Council to carry out its duties and assume its responsibilities."
The ministry also criticised the body's "failure" to turn the Middle East into a region free from weapons of mass destruction, including nuclear arms -- in a reference to Iran and Israel.
Sunni-ruled Saudi Arabia is a fierce critic of Shiite Iran's nuclear programme, which the West and Israel suspect of seeking to develop a nuclear weapon, a charge Tehran denies. Israel is the sole, if undeclared, nuclear power in the region.
Riyadh has been a vocal critic of the UN's handling of the conflict in Syria, where a peaceful movement that called for reforms emerged in March 2011 and was met with a brutal repression and quickly escalated into civil war.
Last month, Saudi Foreign Minister Prince Saud al-Faisal refused to speak or even hand out a copy of his speech at the UN General Assembly in anger over the Security Council deadlock on Syria and Palestine.
"It was a sign of the frustration felt," said Nawaf Obaid, a visiting fellow at Harvard University's Belfer Center and an advisor to Saudi officials.
In addition to its five permanent members, the Security 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 chosen along with Chile, Chad, Lithuania and Nigeria.
Security Council powers had cautiously welcomed Saudi Arabia's election.
"Having them on the Security Council allows you to debate those issues in a way which you can't if they are not on the council," said one UN diplomat.