Bulgaria would allow Russian supply flights to Syria to use its airspace if Moscow agrees to checks of their cargo at a Bulgarian airport, Bulgarian Foreign Minister Daniel Mitov said Wednesday. The Balkan country said Tuesday it had refused a Russian request to use its airspace for the flights due serious doubts about the cargo onboard planes Russia says contain aid for Syria. "If our Russian colleagues agree these flights to be checked at a Bulgarian airport we will issue such a permission," Mitov told reporters.