Boris Johnson has told cabinet that Russia shows “no indication of deescalating” ahead of a press conference in Ukraine.
The prime minister told his top team that the situation on the border of Ukraine was “deeply concerning”.
Meanwhile, the chief of defence staff Admiral Sir Tony Radakin warned cabinet ministers that Russian activity on the border was on a “scale never seen before”.
The PM’s official spokesman said: “The prime minister said the situation was deeply concerning and that there were no indications of Russia deescalating with more than 100,000 troops currently amassed on Ukraine’s border.
“A significant proportion of Russia’s land combat power was now gathered on the western border, coupled with deterrence operation such as military exercises on a scale never seen before.”
“The chief of the defence staff provided an update on the situation, its potential impact on the UK and the action being taken to mitigate the risk and encourage Russia to pursue diplomatic resolution.
“Admiral Sir Tony Radakin said a significant proportion of Russia’s land combat power was now gathered on the western border, coupled with deterrence operations such as military exercises on a scale never seen before.
“He said this fitted into a pattern of coercion and intimidation that sought to undermine the values and principles of the West.”
It comes as the prime minister is set to hold a press conference alongside Ukraine President Volodymyr Zelensky at around 4.45pm UK time.
Ahead of the talks in Kyiv, Johnson announced £88 million of new funding to promote stable governance in Ukraine and reduce its reliance on Russian energy supplies.
Johnson was due to be joined on the trip by foreign secretary Liz Truss, but she will not be travelling after testing positive for Covid on Monday evening.
Yesterday Truss unveiled new legislation on Monday to expand UK sanctions in response to Russia’s aggression towards Ukraine.
The prime minister had also been due to speak to Russia’s president Vladimir Putin on Monday afternoon, but it was postponed after Johnson had to give a statement to the house over the partygate scandal engulfing his government.
Johnson is now expected to hold a phone call with him on Wednesday afternoon.
Ahead of the Ukraine visit, Johnson said: “We urge Russia to step back and engage in dialogue to find a diplomatic resolution and avoid further bloodshed.”
The prime minister was travelling on a chartered plane from Stansted with staff and a small pool of journalists.