At a meeting in Stockholm late on Saturday, the SNC agreed to expand its membership and to hold a vote later this month to elect its leadership, spokesman George Sabra said.
|Abdel Basset Sayda|
The move follows criticism from both within and outside the group that it is failing to unite the diverse opposition forces working against Assad, after more than 17 months of brutal conflict.
"New currents of the opposition will join the SNC. There will be at least five or six new groups from inside and outside Syria" joining the organisation, Sabra said.
The group's general assembly will grow from 300 to 400 members and each opposition group will be represented by 20 members, Sabra said.
Under a reform agreed in Stockholm, the assembly will elect a general secretariat that will then choose an executive bureau and leader for the SNC.
Leaders have previously been chosen by consensus in the group, which brings together diverse regime opponents ranging from liberals to Islamists.
The mandate of current SNC leader Abdel Basset Sayda, which was due to expire on September 9, has been extended and he will stay on until the vote is held in late September, Sabra said.
There were no plans, however, for the SNC to expand to include another prominent opposition grouping, the National Coordination Committee for Democratic Change (NCC), which favours a non-violent overthrow of the regime and opposes foreign military intervention.