On China, which has been accused of repressing its minority Uyghur population and cracking down on rights in Hong Kong, and Russia, Raab said the "door was open" to better ties.
Electoral law stipulates that candidates need to have lived in Syria continuously for at least the past decade, which rules out all exiled opposition figures.
Various platforms for discussion will be held online on Monday and the main donors' round will take place on Tuesday, with the final sum known at the end of the day.
"These girls and boys will be Syria's young adults in five or 10 years and will, in turn, want a future, economic prospects and political freedoms that the system cannot give them if it doesn't reform," he told AFP.
On Monday, the Syrian Army issued a statement that the country's air defenses intercepted "Israeli aggression" over the capital city of Damascus, in the latest surge in the bombardment of alleged Iranian targets inside the country over the past two months.
Witnesses heard large explosions on the southern edge of Damascus, according to local residents.
"Session five of the Constitutional Committee was a missed opportunity and disappointment," Pedersen said of the January meeting, which included the Syrian regime, the opposition and civil society.