Syria's Foreign Ministry has expressed disappointment over remarks made by Britain's Foreign Secretary, Boris Johnson, in which he spoke in support of an opposition-led plan to end the Syrian civil war.

Johnson backed a political transition proposal presented in London by the Syrian opposition which requires Syria's president, Bashar al-Assad, to step down.

According to Johnson, the proposal could help restart peace talks. Syria's Foreign Ministry retaliated, saying Johnson's remarks demonstrated his lack of understanding of the situation in the country.

The multi-sided conflict, which has seen hundreds of thousands of Syrians killed, has persisted for more than five years after an anti-Assad uprising.