Tehran summoned Russia's ambassador on Wednesday over a Moscow-endorsed statement on three Gulf islands disputed by Iran and the United Arab Emirates.
The three isles of Abu Musa, Greater Tunb and Lesser Tunb are claimed by both Tehran and the UAE, but have been held by Iran since 1971 — during the time of the UAE's formation, after gaining independence from Britain.
The UAE renewed demands for the three islands, with UAE Minister of State for International Co-Operation Reem al-Hashimy telling the U.N. General Assembly in September last year that "despite the UAE's sincere calls to peacefully resolve this conflict over the past five decades, we stress here that Iran has not responded. We will never relent in voicing our claim to these islands either through direct negotiations or through the International Court of Justice, as is our legitimate right."
The UAE joins fellow economic Middle East heavyweights Saudi Arabia, Oman, Bahrain, Kuwait and Qatar in the Gulf Cooperation Council. Following a ministerial meeting in Moscow on Monday, Russia and the GCC released a joint statement that urged a diplomatic solution to the territorial dispute.
"The ministers affirmed their support for all peaceful efforts, including the initiative of the United Arab Emirates and its endeavours to reach a peaceful solution to the issue of the three islands, Greater Tunb, Lesser Tunb and Abu Musa, through bilateral negotiations or the International Court of Justice, in accordance with the rules of international law and the United Nations Charter, to resolve this issue is in accordance with international legitimacy," it said, according to the state-owned Saudi Press Agency.
Iran recognized the compulsory jurisdiction of the U.N.'s International Court of Justice late last month.
Tehran's ministry of foreign affairs rejected the statement on Tuesday.
"These islands belong to Iran forever and issuing such statements is in contradiction with the friendly relations between Iran and its neighbors," said Nasser Kanaani, spokesperson for the Iran's ministry of foreign affairs.
"The Islamic Republic of Iran emphasizes the continuation of the policy of good neighborliness and mutual respect, and considers the development and stability of the region to be the collective responsibility of the countries of the region."
Iranian officials called on Russia to correct its position on the territorial row, according to the state-owned Islamic Republic News Agency. The Russian and Iranian foreign ministries did not immediately respond to CNBC requests for comment.
Western sanctions and a dwindling pool of trade partners have brought Moscow and Tehran into a partnership of convenience since Russia's invasion of Ukraine. Russian troops deploy — including in the latest overnight air strikes against Kyiv — Iranian-made Shahed drones in the conflict in Ukraine. Iran denies supplying such weapons to Russia for this purpose. The two nations also cooperate militarily in the conflict in Syria.
Moscow is not Iran's only key partner to wade into hot waters over the three Gulf islands dispute. In December, the ambassador of major Iranian oil buyer China was likewise summoned by Tehran, after Beijing signed a GCC statement that claimed "support for all peaceful efforts, including the initiative and endeavours of the United Arab Emirates to reach a peaceful solution to the issue of the three islands; Greater Tunb, Lesser Tunb, and Abu Musa, through bilateral negotiations in accordance with the rules of international law, and to resolve this issue in accordance with international legitimacy."