UK has warned that NATO is ready for war with Russia.

Alliance countries have supported Ukraine with arms and financial aid since Russia's invasion began but have been careful to avoid any actions that could draw them into the war.

General Sir Richard Barrons, head of Joint force command from 2013-16, was asked in a hearing of the UK parliamentary defence committee on Tuesday at what point Nato would be left with no option but to fight Russia.

He said Nato "will have a call to make" if Russian forces were able to reverse their fortunes and threaten larger parts of Ukraine than they are targeting in the new eastern offensive.