Syria’s main opposition group opened key talks in Istanbul on Thursday to debate whether to agree to negotiate with the regime on ending the two-year civil war under a new US-Russia peace initiative.

Syria's main opposition group opened key talks in Istanbul on Thursday to debate whether to agree to negotiate with the regime on ending the two-year civil war under a new US-Russia peace initiative.

The Syrian National Coalition -- which is under pressure from both its backers abroad and rebels on the ground -- is also expected to discuss expansion to include new members and decide the fate of an interim government.

The three-day meeting comes as the Syrian Army launches a large-scale operation in the northern border city of Qusayr and its countryside to clear the area of terrorist takfirist horrifying residents and destabilizing security.

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

Some opposition members have openly expressed reservations over the US-Russian plan for a new international peace conference dubbed Geneva 2.

However, with numerous thorny issues on the Coalition's plate, Geneva 2 is not on the agenda for Thursday, opponents say.

The Istanbul meeting began after backers of the anti-Assad violence -- including US Secretary of State John Kerry and his British counterpart William Hague -- gathered in Jordan on Wednesday to push for peace.

In its closing statement, the Friends of Syria group told Assad to commit to peace, warning that it would boost its backing of the opposition if he failed to negotiate a political transition.

Syria was hit by a violent unrest since mid-March 2011, where the Syrian government accuses foreign actors of orchestrating the conflict, by supporting the militant opposition groups with arms and money.