Russia 'could reach capability for full-scale invasion of Ukraine by late February'

Russia could reach the capability required for a full-scale invasion of Ukraine by late February, according to a UK defence source.

ITV News Global Security Editor Rohit Kachroo reported the official as warning: "Despite diplomatic efforts, the Russian Army continues to mass".

Separately, US officials have said Russian forces have assembled at least 70 per cent of the military firepower it likely intends to have in place by the middle of the month.

Watch ITV News Correspondent Dan Rivers' report from separatist Ukraine, which has been touched by conflict for eight years

Speaking anonymously, the officials stressed that a diplomatic solution appears to remain possible.

US officials have said in recent weeks that a Russian invasion could overwhelm Ukraine's military relatively quickly, although Moscow might find it difficult to sustain an occupation and cope with a potential insurgency.

ITV News understands Kyiv could fall "within days" according to separate UK official.

How many Russian troops are amassed on the border with Ukraine?

As of Friday, US officials said, the Russian army has put in place near Ukraine a total of 83 "battalion tactical groups".

Each of these is roughly equivalent in size to a battalion of between 750 and 1,000 soldiers.

That is an increase from 60 battalion tactical groups in position just two weeks ago, they said.

Another 14 battalion tactical groups are on their way to the border area from other parts of Russia, the officials said.

Sources said the US assesses Russia would want a total of between 110 and 130 battalion tactical groups for use in a full-scale invasion, but Putin could decide on a more limited incursion.

Including support units, Russia might be aiming to have 150,000 troops in place for a full-scale invasion, one official said, adding that the ongoing buildup could reach that level in the next couple of weeks.

On the lower end of the scale of military action, Putin might order sabotage, cyberattacks and other destabilizing actions inside Ukraine with the goal of removing the current government in Kyiv, officials have said.