The National Coalition for Syrian Revolutionary and Opposition Forces was unveiled in Doha on Sunday.
Its president will be Moaz al-Khatib, a former imam of the Umayyad Mosque in Damascus who fled Syria this year.
Meanwhile, Syrian government aircraft bombed the rebel-held town of Ras al-Ain, near the border with Turkey.
Both jets and helicopters targeted the town, sending civilians fleeing into the Turkish settlement of Ceylanpinar. Casualties were reported.
Observers and activists estimate that more than 36,000 people have been killed in the long-running uprising against President Assad. Hundreds of thousands have sought refuge in neighboring countries.
International recognition
Western and regional powers have in recent weeks put pressure on a hitherto fractious Syrian opposition to create a unified, credible body that could become a conduit for all financial and possibly military aid.
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