He said many African and poorer countries relied heavily on Russian and Ukrainian wheat production, now endangered by the conflict.

These include Burkina Faso, Somalia and Yemen which are already struggling to feed their populations.

Mr Guterres called for an immediate ceasefire to avoid a breakdown of the world food systems.

He also announced a $40m (£31m) package to help millions of Ukrainians facing hunger and dwindling supplies of water and medicine