TEHRAN — The United States launched an extensive campaign to pressure countries into staying away from the funeral ceremonies for Iran's martyred Leader, a senior Iranian official has revealed, as nearly 100 nations ultimately defied Washington and sent delegations to Tehran.

According to a senior source who spoke to the Tasnim news agency, U.S. officials at the highest levels conducted a five-day campaign aimed at discouraging foreign governments from attending the commemorations for Ayatollah Seyyed Ali Khamenei, who was martyred in U.S.-Israeli strikes on February 28.

Secretary of State Marco Rubio issued a confidential directive on June 26 to all U.S. embassies and diplomatic missions, the source said, instructing diplomats to "use all available capacities of the United States" to persuade host country officials that participation in the funeral would be considered "an unfriendly act" by Washington and carry "negative consequences for bilateral relations with the United States."

Two Arab diplomats, speaking on condition of anonymity to Tasnim, confirmed that Rubio personally contacted his counterparts in at least five Arab countries to press them to stay away.

U.S. ambassadors in African countries went further, explicitly threatening to cut development aid should their host nations send representatives to Tehran, according to the Iranian source. This pressure campaign, the source said, was the reason one major North African country reduced the level of its participation in the ceremonies.

Despite the aggressive U.S. push, delegations from nearly 100 countries ultimately attended the funeral proceedings on Friday.

However, according to Iranian assessments, at least 13 countries ultimately succumbed to U.S. pressure and withdrew their participation. These included three Eastern European nations, five African countries, two Arab states in the Persian Gulf, and two major East Asian nations, the source said.

Some of the countries that withdrew under U.S. pressure reportedly attempted to apologize and justify their decisions through intermediaries or via their diplomatic missions in Geneva and New York. A number of others offered to send lower-level diplomats already stationed in Tehran, but Iran declined to accept them, the source added.

The revelations come as the funeral ceremonies continue to draw massive crowds across Iran, with millions taking to the streets to mourn the Leader and other victims of the opening U.S.-Israeli strikes, including his 14-month-old granddaughter.