Moscow is waiting for explanations from Sofia following the closure of the Bulgarian airspace for Russian transport planes carrying humanitarian aid to Syria, Sputnik quoted Kremlin spokesman Dmitry Peskov as saying Tuesday.

Bulgaria's Foreign Ministry confirmed earlier on Tuesday that it had banned Russian military transport planes carrying supplies to Syria from entering the country's airspace until September 24, citing concerns over "the purpose of the flights and the cargo".

Peskov stressed that Moscow would not comment on Bulgaria's claims that the supplies could be of military nature.

Source: MENA