The pro-Iranian government academic Prof Mohammad Marandi has said Iran has been crucial in stopping the advance of so-called Islamic State.

Prof Marandi from the University of Tehran said: "If it wasn't for Iran there would be black flags in Damascus today" - a reference to the black flags of IS.

He told Hardtalk's Zeinab Badawi: "If Iran had not supported Syria and the people in Lebanon we would not have a Syria today and we would not have a Lebanon and we probably would not have an Iraq."

The new US administration has "put Iran on notice" after it recently tested a missile and has also warned against Iran’s "destabilising behaviour" across the Middle East.

US Secretary of Defence James Mattis said recently that Iran was "the single biggest state sponsor of terrorism in the world".

You can see the interview in full on Wednesday 22 February on BBC World News and the BBC News Channel and after on BBC iPlayer (UK only).