Egyptian President Mohamed Morsi on Wednesday urged Syrian opposition groups to unify, as he addressed leaders of Islamic states at a summit that also tackled the battle against militants in Mali.

"The Syrian regime must draw lessons from history: it is the people who remain. Those who put their personal interests above the interests of their people will end up leaving," Morsi told heads of state and representatives of the Organisation of Islamic Cooperation in Cairo.

Morsi called on opposition parties not allied to Syria's National Coalition, which is recognised by the international community, "to coordinate with this coalition and support their efforts for a unified approach... for democracy."

The meeting gathers leaders of 26 of the OIC's 57 states, with Morsi, Egypt's first Islamist president, assuming the organisation's rotating presidency.

Though Syria is not represented at the conference, much of the debate was expected to focus on the conflict there in which according to the United Nations more than 60,000 people have died in almost 23 months.

According to a draft resolution obtained by AFP, the gathering will call for "serious dialogue" between the Syrian opposition and government officials "not directly involved in oppression".

The call for dialogue, drafted by foreign ministers after two days of preparatory meetings, will pile pressure on Syrian President Bashar al-Assad to respond to a surprise offer of talks by Ahmed Moaz al-Khatib, leader of National Coalition.

The document stresses the need to maintain "Syria's territorial integrity and sovereignty", while underlining that "the main responsibility for the continued violence falls on the Syrian government".

The attendance of Mahmoud Ahmadinejad, in the first visit to Egypt by an Iranian president since Iran's 1979 Islamic revolution, could complicate debate.

Iran is the chief regional backer of Assad, while Egypt and Gulf powerhouse Saudi Arabia bitterly oppose the Syrian president and support rebels seeking his ouster.

A meeting is scheduled between Egypt, Iran, Turkey and Saudi Arabia -- members of a quartet dealing with Syria -- on the sidelines of the summit.

The meeting had been scheduled to take place in 2011 but was postponed due to the regional uprisings that overthrew four Arab dictators, including Egypt's president Hosni Mubarak, the OIC's secretary general Ekmeleddin Ihsanoglu said.

The Cairo summit will also discuss the conflict in Mali, where France is pursuing attacks against Islamist militants.

Egypt and Qatar have in the past said that the conflict in Mali needed to be resolved politically.

The Islamic leaders will also discuss the issue of Israeli settlements on occupied Palestinian territory, a subject regularly brought up at OIC summits since the organisation's creation in 1969.

The questions of Islamophobia, Muslim minorities in the world and economic cooperation in the Islamic world are also on the agenda.

Sectarian tensions between the Islamic world's Sunnis and Shiites were brought to the surface on Tuesday during Ahmadinejad's visit to Al-Azhar, Sunni Islam's highest seat of learning.

Senior Al-Azhar clerics launched into a tirade against "some Shiites" for insulting some of the Prophet Mohammed's companions as the Iranian president listened with noticeable unease.

Ahmadinejad was also targeted by a shoe-throwing protester as he left a Cairo mosque. Four people have been detained over the incident, a security official said.