ISTANBUL (AFP) - Syria's main opposition group said on Thursday that it will not take part in proposed US-Russia peace talks while key allies of President Bashar al-Assad's regime are waging war alongside government forces.

"The National Coalition will not take part in any international conference or any such efforts so long as the militias of Iran and Hezbollah continue their invasion of Syria," the opposition's acting chief George Sabra told reporters in Istanbul.

It has taken the divided opposition meeting in Istanbul a week to find common ground on the so-called Geneva 2 peace conference proposed by Moscow and Washington.

The group has previously said it was open in principle to any peace initiatives.

Mr Sabra's comments follow Syrian army advances in areas where the Lebanese militia group Hezbollah has joined troops loyal to Assad.

"In light of this savagery, any talk of an international conference or a political solution in Syria is just meaningless chatter," he said.

His statement came hours after the coalition launched an urgent appeal to rescue 1,000 wounded civilians from the town of Qusayr in central Syria.

Government troops and Hezbollah fighters have been battling for more than a week to retake Qusayr from rebel hands.