Brigadier General Manaf Tlas, one of the most senior defectors from President Bashar al-Assad's rule, said he would help unite Syria's fragmented opposition inside and outside the country to agree a roadmap for a transfer of power.
Tlas, speaking in a newspaper interview in the Saudi city of Jeddah, also said he was looking for support from Saudi Arabia and other powers.
"I am discussing with...people outside Syria to reach a consensus with those inside," Tlas told the Saudi newspaper Asharq al-Awsat. "I left (Syria)...to try to help the best I can to unite the honourable people inside and outside Syria to set out a road map to get Syria out of this crisis".
Tlas, a former friend of Assad's who could play a role in any transition of power, said he "did not leave Syria to lead the transitional period".
"I realise this is a difficult phase... It's difficult for one person to bear the responsibility of such a phase," he said.
"A group (including opposition) from inside and outside Syria should cooperate to accomplish this phase."
The general, a Sunni Muslim member of Assad's mostly Alawite inner circle and a senior officer in the Republican Guards, defected earlier this month.