Sudan faces an “all-out catastrophe” if its rival factions do not make peace, David Lammy has warned.

He has also announced a foreign ministers’ summit to be held in London, aimed at tackling the country’s disastrous civil war.

The Foreign Secretary told The Telegraph he was inviting counterparts including Marco Rubio, the US secretary of state, to try to find a “pathway to peace” for the two-year-long conflict.

The warring factions themselves are not invited, but several of their backers are expected to attend in an attempt to find “international consensus” to ending a war that analysts say has become a bloody free-for-all of competing regional powers.

The summit is being jointly organised with France, Germany and the African Union, and will be held next week on the second anniversary of a conflict which has tipped Africa’s third-largest country into a humanitarian crisis.