Syria's main Western-backed opposition coalition says it will take part in peace talks with the government if certain conditions are met, including allowing aid workers to access besieged areas.
The Syrian National Coalition announced its decision in a statement Monday after two days of talks in Istanbul.
U.S. Secretary of State John Kerry praised the announcement, saying the group's participation would be a "big step forward."
The group wants the government to guarantee the establishment of humanitarian corridors, the release of detainees and for the peace negotiations to result in a political transition in Syria.
Opposition members have long demanded that President Bashar al-Assad have no part in the transitional government that the United States and Russia want the two sides to agree on in the Geneva peace talks.
No date has been set for the proposed conference, which has been repeatedly delayed as U.S., Russian and U.N. diplomats struggle to get the two sides to agree to take part.
Coalition members want the backing of rebel fighting units, community leaders and activists inside Syria to counter criticism that they are out of touch with those battling on the ground.
Major Islamist rebel brigades have declared their opposition to the Geneva process if the conference does not result in Mr. Assad's removal. Some have said they would charge anyone who attended the planned international talks with treason.