"There will be three main topics: Idlib, release of detainees and constitutional commission," Toma said.
The decision to set up the constitutional commission was made at the Syrian congress held in Sochi in late January.
The delegation of the Syrian opposition for the talks in Sochi comprises around 10 people and is headed by Toma, official spokesman for the delegation Ayman Asimi said. Sochi is hosting the 10th high-level meeting of the guarantor states on Syria in the so-called Astana format.
Toma is the representative of the National Coalition for Syrian Revolutionary and Opposition Forces and the former head of the "interim government" that the coalition proclaimed. The delegation of the Syrian opposition is expected to arrive in Sochi in early hours of Monday.