President Morsi demanded the withdrawal of the Lebanese militant movement Hezbollah from Syria
Syria has condemned Egyptian President Mohammed Morsi for cutting off diplomatic relations between the two countries.
Mr Morsi had joined a "choir of conspiracy and incitement led by America", an "official source" told the state-run Sana news agency.
Mr Morsi also demanded that the Lebanese Shia movement Hezbollah withdraw from the fighting in Syria.
Some Sunni Muslim clerics have urged support for rebels in Syria.
Addressing a rally in support of the Syrian opposition on Saturday, Mr Morsi said that Syria's embassy in Cairo would be shut and Egypt's representative withdrawn from Damascus.
He also called on the international community to impose a no-fly zone over the country.
Syria said the move was "irresponsible" and was part of an attempt to "implement a Muslim Brotherhood agenda" designed to deflect attention from Egypt's internal problems.
Sunni clerics from several Arab countries issued a statement after a meeting in Cairo on Thursday calling for "jihad to help our brothers in Syria by sending them money and arms".
"The flagrant aggression of the Iranian regime, of Hezbollah and of their sectarian allies in Syria amounts to a declaration of war against Islam and Muslims," the statement went on.
Also on Sunday, Syrian President Bashar al-Assad congratulated Hassan Rouhani on his election as president of Iran.
Mr Assad reiterated Syrian's "willingness to continue improving friendly relations between the two countries", Sana reported.
The UK's Independent newspaper reported that Iranian officials had decided to send 4,000 troops to back Mr Assad's forces in Syria. Iran has been one of Mr Assad's key international backers.
A recent report from a US think tank said Iran had been providing training in internal security and counter-insurgency operations to the Syrian government, as well as providing material supplies.
Russian anger
Hezbollah's involvement in the conflict in Syria was also condemned by the Arab League and the UN Human Rights Council after the Lebanese movement's role in the retaking of the key town of Qusair from rebel forces earlier this month.
Syrian pro-government media have reported that the military is preparing for a major offensive on the northern city of Aleppo after recapturing Qusair.
On Saturday the US announced it would keep Patriot missiles and F-16 fighter jets in Jordan after a military exercise, angering Russia.
Russian Foreign Minister Sergei Lavrov warned that any attempt to use the F-16s to impose a no-fly zone over Syria would violate international law.
Moscow and Washington are attempting to persuade the government and opposition to attend an international conference to find a political solution to the two-year-old conflict which the UN says has left more than 93,000 people dead.
Russian President Vladimir Putin is due to meet UK Prime Minister David Cameron on Sunday before holding talks with US President Barack Obama at a G8 conference in Northern Ireland on Monday.
The leaders are expected to discuss Syria, including the US decision this week to begin sending weapons to rebel forces.
Source BBC News
Bashar al-Assad Latest News Middle East Mohammed Morsi syria crisis syria news war news