RIYADH, SAUDI ARABIA - The secretary-general of the Saudi-based Organization of Islamic Cooperation has resigned after making a joke about the purportedly frugal ways of Egypt's president, the group said.

The joke became the latest point of contention in Cairo's increasingly tense relations with Riyadh.

The OIC said late Monday that Iyad bin Amin Madani, a Saudi, resigned "for health reasons." On Tuesday, the Saudi daily Asharq Al-Awsat said Riyadh has nominated former Social Affairs Minister Youssef Ben Ahmed al-Othimein to replace Madani.

Madani, during an OIC meeting last week, confused the Tunisian president's name — Beji Caid Essebsi — with that of Egyptian President Abdel-Fattah el-Sissi.

Addressing Essebsi, he then said: "I am sure your fridge has more than water."

It was a reference to a comment recently made by Sissi claiming that for a decade his fridge had nothing but water— a message to Egyptians to endure the harsh economic conditions their country is experiencing.

Madani's joke angered the Egyptians, with Foreign Minister Sameh Shukri declaring that it had cast doubt on Madani's ability to run the OIC — the world's largest body of Islamic nations with 57 members. Shukri also said Egypt would "revise" its approach to the OIC and its chief.

Egyptian media, meanwhile, claimed Madani was a supporter of the Muslim Brotherhood, an Islamist group from which Egypt's ousted President Mohamed Morsi hails. Sissi led the military's 2013 overthrow of Morsi, Egypt’s first democratically elected civilian president. Authorities have since jailed Morsi, as well as thousands of his supporters, and branded the Brotherhood a terrorist organization.

Since 2013, Saudi Arabia spent billions of dollars to keep Egypt's ailing economy afloat but relations between them later soured, mainly because of differences over the wars in Syria and Yemen, and economic issues.

Last month, the Saudis abruptly halted previously agreed fuel shipments, for which Egypt was given soft repayment terms. There has been no word on their resumption.