An emergency summit of the 57-member Organisation of Islamic Cooperation (OIC) began late Tuesday with a proposal to suspend conflict-wracked Syria, a move strongly opposed by Iran.

A draft final statement obtained by AFP said the summit "approves the suspension of Syria's membership," a measure recommended by a preparatory ministerial meeting held Monday in the western Saudi city of Jeddah.

The move would further isolate President Bashar al-Assad's embattled regime, after Syria was suspended from the Arab League last year over its brutal crackdown on an Arab Spring-inspired revolt launched in March 2011.

The OIC represents 1.5 billion Muslims worldwide, and its suspension of Syria would heap pressure on Assad, who has characterized the uprising as a plot by Western and rival powers to overthrow his Iran-allied regime.

Saudi King Abdullah -- who initially proposed the suspension of Syria -- is presiding over the meeting held in Mecca, the holiest Islamic city.

Iranian President Mahmoud Ahmadinejad, whose country has openly criticised the push to suspend Syria, is attending the extraordinary meeting and was expected to strongly oppose the move to suspend Damascus.

The draft statement says Syria should be suspended over "the obstinacy of the Syrian authorities in following the military option" to solve the crisis and the failure of a UN-Arab League peace plan brokered by Kofi Annan.

It demands that Assad's regime "immediately end all acts of violence" while defending Syria's "unity, sovereignty, independence and territorial integrity."

Tensions have been simmering for months between Sunni-dominated Saudi Arabia and Shiite-dominated Iran as Syria has emerged as another arena for the longtime rivalry between the two regional heavyweights.

Saudi Arabia, which hosts the OIC's headquarters in the Red Sea city of Jeddah, has openly called for arming Syrian rebels.

Tehran meanwhile accuses Saudi Arabia, Qatar and Turkey of arming and financing the mainly Sunni rebels against Assad, who leads a regime dominated by members of his Alawite sect, an off-shoot of Shiite Islam.

Iran is the Syrian regime's biggest regional ally and has pledged its full support for Assad, though it denies US and rebel accusations that it is providing his regime with arms and fighters.

Iranian Foreign Minister Ali Akbar Salehi on Monday criticised the move to suspend Syria's membership of the OIC, saying it would not resolve the conflict and was not in line with the group's charter.

"We have to look for other ways, means and mechanisms for resolving conflicts and crises," he said, calling for a "Syrian-Syrian solution" reached through negotiations between the government and the rebels.

But foreign ministers meeting ahead of the summit agreed to suspend Syria "based on consensus with an absolute majority" and forwarded the decision to heads of state for final approval, OIC chief Ekmeleddin Ihsanoglu said.

Sources close to the meeting said that only Iran and Algeria were against the recommendation. Syria had no representative at the meeting.

Mohammed Ahmed Taieb, a top Saudi foreign ministry official, said that some delegates believed the body should go further by demanding that Assad step down and "preparing for a post-Assad transition period."

Tunisian Foreign Minister Rafik Abdessalem hailed the move to suspend as "a strong message to the Syrian regime on the importance of listening to the will of the people and their demands for freedom, justice and dignity."

The United States said that special envoy to the OIC Rashad Hussain would take part in the summit as an observer and meet with delegates on the sidelines.

The State Department said his attendance demonstrates Washington's commitment to "bring additional pressure to bear on the Assad regime."

The 17-month conflict in Syria has killed more than 21,000 people, according to rights groups.

In addition to the Syrian crisis, the OIC was also to discuss the Arab-Israeli conflict, the violence against the Muslim Rohingya minority in Myanmar and the unrest in Mali.

The meeting has added significance as it is being held on the 26th night of the fasting month of Ramadan, the night Muslims believe the Koran was revealed to the Prophet Mohammed.

Hundreds of thousands of Muslims flooded Mecca on Tuesday as prayers went on until the early morning hours.

Security forces were massively deployed across the city as one of them held a banner at the entrance of the Grand Mosque reading: "The Grand Mosque is full, please pray outside to ensure your own safety."

Saeed al-Khathami, a member of the security forces, put the numbers of worshippers on Tuesday night at around "four or five million people."

Outside the mosque, streets crammed up with tens of thousands who lined up to pray in the open as beggars sat along the pavements hopefully eyeing passers-by willing to give away some money in return for Allah's reward.

"On this holy night, God fulfills all our prayers," said one 36-year-old woman who came from Egypt to perform the minor pilgrimage. "I prayed for Egypt's glory and victory for all Muslims, especially those in Syria."