France's foreign minister says Syria's air force is using so-called barrel bombs — makeshift weapons consisting of containers stuffed with TNT — to heavily damage neighborhoods.

Laurent Fabius said Wednesday that Syrian leader Bashar Assad's regime has "entered a new phase in the violence by using MIG (aircraft) and dropping barrels of TNT."

He confirmed what delegates from rebel-held zones in Syria were saying as a meeting got under way in Paris aimed at extending a French initiative of direct aid to local councils in so-called liberated zones of Syria. Some 20 countries were taking part in the meeting.

Earlier this month, Syrian refugees said their villages in Homs province had come under heavy air attack from barrel bombs.