Sky.com has comments from former General Staff chief Lord Dannatt:

“I think it’s only a matter of time before Mariupol falls completely under Russian control.

“This is going to be a very gruesome and sad end to a very heroic fight by the Ukrainian soldiers.

“Then, of course, the Russians will have achieved one of their strategic objectives, which is to create that land corridor from Crimea, through Mariupol, to the Donbas region which borders Russia proper.

“Securing a land corridor from Crimea – which it secured in 2014 but hitherto has only been accessible by sea. They will have joined up the dots, if you like.”

Lord Dannatt says “Russia will not want to give that up”, offering a hint on what the future could hold for this war.

“Over time Ukraine may have to accept that it’s lost part of its territory,” he says.