Iranians rallied Friday to denounce efforts by Bahrain's Sunni rulers to forge closer ties with Saudi Arabia, a pact the Shiite powerhouse Iran claims would go against the will of the tiny island nation's majority Shiites.

Iran's anger is directed at archrival Saudi Arabia, which has been acting as a protector of Bahrain's ruling Sunni dynasty. It was set off by efforts earlier this week by Gulf Arab states to outline closer political and security ties among their nations.

Though a decision on a Gulf Arab pact was postponed at a meeting in Riyadh on Monday, the gathering itself upset Tehran, which summoned Bahrain's top diplomat in the country late Thursday to relay its concerns, the official IRNA news agency reported.

Bahrain has been rocked by an uprising in which the Shiite-led opposition seeks to overturn the wide-ranging powers of the ruling Sunni dynasty. At least 50 people have died in the unrest since February 2011.

Bahrain's rulers and their patron Saudi Arabia accuse Iran of encouraging the protests, claims that Tehran has denied. Iran and Bahrain have occasionally summoned each other's envoys since the beginning of Bahrain's unrest.

Last year, Saudi forces led 1,500 Gulf troops into Bahrain to help prop up the Sunni dynasty against the uprising, now in its 15th month. The result has been a virtual melding of the two countries on the ground — with the Saudi and Bahraini flags often displayed in unison at the airport and some security checkpoints.

Opposition groups in Bahrain, however, have strongly denounced the calls for tighter bonds with Saudi Arabia and possibly other Gulf states.

Friday's government-backed march followed midday prayers in Tehran, led by cleric Kazem Sedighi who said a Saudi-Bahraini pact would be an "ominous conspiracy" aimed at the "annexation" of Bahrain by Saudi Arabia.

"Bahrain and regional nations, as well as the Muslim world and the Iranian nation will never accept the conspiracy," Sedighi said.

State television said similar rallies took place in other cities and towns in Iran, with thousands participating.

Many nationalist and hard-line conservatives in Iran consider Bahrain, which gained independence from Britain in 1971, as a rightful part of the Persian country as it was before it fell under Britain during colonial times.

Until 1971 and under the Western-backed Shah Mohammad Reza Pahlavi who was toppled by the 1979 Islamic Revolution, Iran kept two empty seats in its parliament for supposed representatives from "Bahrain province."

On Sunday, about 190 lawmakers — more than half the Iranian parliament — issued a statement condemning the Gulf Arab union plans.