Russia on Friday sharply criticized Saudi Arabia for rejecting membership of the UN Security Council, slamming the kingdom's "strange" argument that the body had failed over the Syrian conflict.
Moscow's traditionally testy relationship with Riyadh has become even more strained in recent years, with the two countries at loggerheads over Saudi support for the rebels battling the pro-Kremlin regime in Syria.
"We are surprised by Saudi Arabia's unprecedented decision" to reject the seat, the Russian foreign ministry said in a statement.
"In this way, Saudi Arabia has excluded itself from collective work within the Security Council to support international peace and security."
It added: "The kingdom's arguments arouse bewilderment and the criticism of the UN Security Council in the context of the Syrian conflict is particularly strange."
Saudi Arabia earlier Friday rejected temporary membership of the Security Council -- where Russia holds a permanent, veto-wielding seat -- and accused the body of "double-standards" in resolving conflicts like Syria.
The Russian foreign ministry noted that in late September the Security Council had adopted a resolution on clearing Syria of its chemical weapons arsenal.
However previously, Moscow had blocked all moves to punish the regime of Bashar al-Assad.
The most significant high-level contact between Russia and Saudi Arabia in recent months was a meeting between President Vladimir Putin and Saudi Arabia's influential intelligence chief Prince Bandar bin Sultan in Moscow on July 31.
Diplomats in the Middle East have said that Putin rejected a proposal from Prince Bandar for Moscow to abandon its support for Assad in exchange for a huge arms order from Riyadh worth $15 billion. Putin rejected the proposals, according to the same sources.
However the Kremlin later denied that the two men had discussed military cooperation or any deals.
Widely regarded as among the most influential powerbrokers in the entire Middle East, Prince Bandar is the son of the late crown prince Sultan bin Abdul Aziz, who died in 2011.