There are growing signs Russia could be on the brink of fully capturing Mariupol, the besieged southern port city which has suffered a devastating, six-week assault.

Officially, Ukraine’s armed forces say they are sustaining its defence and are in “continuous contact” with their troops on the ground. But they concede it is likely Moscow will try to take full control of the city, while a regional Russian-backed separatist leader claims Mariupol is close to falling.

Ukrainian troops have said they are running out of ammunition, and are believed to have been pushed back into two isolated pockets adjoining the coastline.