Syria's main political opposition group, the Syrian National Coalition (SNC), has agreed to attend next week's so-called Geneva II peace talks, to be held in Montreux.
But the debate over whether to send representatives to the talks has split the coalition.
The BBC reports SNC representatives took the decision at a meeting in the Turkish city, Istanbul.
The aim of the talks is to start the process of setting up a transitional government to end the war in Syria.
The three-year conflict has claimed the lives of more than 100,000 people.
An estimated 2 million people have fled the country and some 6.5 million have been internally displaced.
Of the delegates who voted, 58 were in favour, 14 were against, while one abstained.
Syrian opposition figures had earlier expressed reluctance to go to Switzerland unless President Assad was excluded from any future transitional government.