Iran has called on the UN Security Council to protect opposition activists in Bahrain, where, it said, unrest and suppression could destabilise the entire region, the official IRNA news agency said on Friday.
Tehran has been outspoken in its criticism of the Bahraini ruling family's violent suppression of pro-reform protests. Bahrain's Gulf Arab allies, some of which intervened militarily and sent troops to the island state to bolster government forces, have accused the Islamic Republic of interference.
In a letter to UN Secretary-General Ban Ki-Moon, Iranian Foreign Minister Ali Akbar Salehi called for "a serious and immediate action by the Security Council over suppressing people's demands in Bahrain using military force".
"The Islamic Republic of Iran cannot stay indifferent towards events in Bahrain and their consequences, because the situation could be uncontrollable if the current situation goes on," Salehi wrote.
"Such consequences would destabilise the Persian Gulf region and of course its aftermath would affect the world."
Bahrain has launched a security crackdown after its police forces quelled weeks of pro-democracy protests which it accuses Iran of fomenting. The opposition says hundreds have been arrested and four have died in police custody over the last two weeks.
The Bahrain crisis has accentuated tensions between non-Arab Iran and its Arab neighbours across the Gulf, particularly Saudi Arabia which provides 12 percent of U.S. crude imports and is seen by Washington as a counterweight to the Islamic Republic.
Salehi complained to the United Nations last month after Saudi troops entered Bahrain as part of an effort by the six-nation Gulf Cooperation Council to help quell the protests, saying Riyadh was using the protests as a "pretext for intervention".
At Friday prayers in Tehran, hardline cleric Ahmad Jannati backed Salehi's comments and warned Saudi Arabia against provoking Iran.
"Hatred towards Saudi Arabia is spreading," Jannati told worshippers. "People really hate these Wahhabis," he added, a reference to the dominant form of Islam in Saudi Arabia.
Gulf Arab countries are concerned over what they see as the ambition of Iran, a Shi'ite power, to extend its influence in Arab countries mostly under Sunni rule.
Kuwait said this week it had expelled three Iranian diplomats for involvement in a spy ring, and in a tit-for-tat move Tehran gave three Kuwaiti diplomats 10 days to leave Iran.
Last month, a Kuwaiti court sentenced two Iranians and a Kuwaiti to death for being part of the alleged spy ring. Iran denies the accusations of spying or interfering in other countries' affairs.