The toppling of Syrian President Bashar al-Assad in the "wrong way" would be "a nightmare" the former White House co-ordinator for Middle East policy Philip Gordon has told BBC HARDtalk.

Syria would be a better place without President Assad said Mr Gordon, but he warned that institutions and a diplomatic framework would need to be preserved if he was removed.

"If he is toppled by some combination of opposition groups led by the Al-Nusra Front, which is essentially al-Qaeda in Syria, and ISIS then you would not have this stable, friendly regime in Damascus, but all out civil war," he said.