Syria's outgoing opposition chief has published an initiative for his war-torn country that would grant President Bashar al-Assad a safe exit, and urged dissident factions to adopt his plan.

Moaz al-Khatib published his initiative on Facebook on Thursday, as the Syrian National Coalition (SNC) he headed until March gathered in Istanbul to choose a new leader and discuss a US-Russian peace initiative dubbed Geneva 2.

Under Khatib's initiative, Assad would have 20 days from Thursday to give "his acceptance of a peaceful transition of authority".

After accepting, Assad would have one month to hand over power to either Prime Minister Wael al-Halqi or Vice President Faruq al-Sharaa, who would then govern Syria for a transitional period of 100 days.

Khatib's proposal is an effort to pull Syria "out from the catastrophe that has struck our nation", said the former imam of Damascus' Omayyad mosque.

It came as the SNC opened a three-day meeting in Istanbul to debate whether to agree to negotiate with the regime on ending the two-year civil war in the Geneva 2 conference, expected to take place next month.

Talks with regime

The opposition has long said it can only enter into talks with members of the regime if it is given international guarantees that the negotiations would lead to the fall of Assad's regime.

In Cairo, the Arab League said in a statement it would submit a list of points to the UN Security Council “to help the next international conference in Geneva succeed”.

Thursday’s statement did not say what the points were, but officias - who spoke to AFP news agency on condition of anonymity - said the proposal would include forming a temporary national unity government and deployment of a UN peacekeeping force in Syria "to guarantee stability during the transitional period".

Some opposition members have openly expressed reservations over the Geneva 2 conference.

"We don't have a clear picture on Geneva 2. We don't have a list of attendees, we don't know what countries are going to attend, what's the agenda, what's being proposed, what are the final goals," SNC spokesman Khaled al-Saleh told reporters.

On Khatib’s proposal, Saleh said it was a "personal initiative" that would be "submitted at the coalition meeting and maybe discussed".

As part of the transition Khatib envisages, Assad would "leave the country along with 500 people whom he will select, along with their families and children, to any other country that may choose to host them".

This is the first time one of Syria's opposition chiefs has made an offer of political immunity to Assad and key members of his regime.

'Practical response'

It is "a practical response to the need of a political settlement ensuring a peaceful transition of authority", Khatib said.

The initiative gives Assad a month to "completely hand over authority", and stipulates that while parliament should be dissolved, all of its powers should be handed to Assad's replacement.

Over the same 100-day period, an interim government would "restructure the security and military" apparatus in Syria, said Khatib.

He also suggested that the UN should appoint an international mediator to oversee the transition.

At the end of the 100 days, the responsibilities of the current government would pass to the transitional government, formed with international guarantees, which would "be responsible for the preparation and the re-building of the new Syria," Khatib said.

In Istanbul, the SNC was seeking to establish an opposition government under interim prime minister Ghassan Hitto, while discussing the group's expansion to include 31 new members, a Coalition source told AFP on condition of anonymity.

Hitto has pulled together a list of ministries and representatives for all but the interior and defence portfolios - but his proposals may not even see the light as he too may end up being replaced, the official added.