Cairo - Egyptian President Mohamed Mursi said he had cut all diplomatic ties with Damascus on Saturday and backed a no-fly zone over Syria, pitching the most populous Arab state more firmly against President Bashar al-Assad.
Addressing a rally called by Sunni Muslim clerics in Cairo, the Sunni Islamist head of state also warned Assad's ally, the Iranian-backed Lebanese Shi'ite militia Hezbollah, to pull back from fighting in Syria.
"Hezbollah must leave Syria. These are serious words," said Mursi, whose country hosted a conference of Sunni clerics this week who issued a call for holy war against Damascus.
"There is no space or place for Hezbollah in Syria," Mursi said.
The rally underscored the region's deepening sectarian rift. A cleric who spoke before Mursi described Shi'ites as heretics, infidels, oppressors and polytheists.
It was also a show of support for Mursi as his opponents mobilise for protests to demand early presidential elections.
Mursi waved Syrian and Egyptian flags as he entered the auditorium packed with 20 000 supporters. The crowd chanted: "From the free revolutionaries of Egypt: We will stamp on you, Bashar!"
Mursi, a Muslim Brotherhood politician, steered clear of direct references to Shi'ites and Iran but in a partial allusion to Tehran, he accused states in the region and beyond of feeding "a campaign of extermination and planned ethnic cleansing" in Syria.
"We decided today to entirely break off relations with Syria and with the current Syrian regime," he said. He also urged world powers not to hesitate to enforce a no-fly zone over Syria.