The UK is doing “everything possible” to support the people of Ukraine in the face of a Russian “disinformation campaign”, Boris Johnson said.

The Prime Minister told the Cabinet that Russian president Vladimir Putin “must not be allowed to rewrite the rules” of international relations as tensions continued to mount.

The UK has promised anti-tank weapons to Ukraine in response to a Russian military build-up on the border, with around 100 British troops involved in a training operation.

The Prime Minister’s official spokesman said Mr Johnson addressed the situation during Tuesday’s Cabinet meeting.

“He said the UK is doing everything possible to support the Ukrainian people in the face of a disinformation campaign from Russia aimed at undermining its sovereign neighbour.

“The UK remains open to further talks with Russia.

“The Prime Minister said that President Putin must not be allowed to rewrite the rules and that as a free democracy must continue to be allowed to aspire to Nato membership.”

Defence Secretary Ben Wallace told MPs on Monday that the UK was supplying light anti-armour defensive weapons, with a “small number” of UK personnel travelling to the country to provide training.

The Prime Minister’s official spokesman said: “There is a small infantry training team deploying to assist the Ukrainian armed forces to become familiar with the defensive systems we are providing and ensure they are able to use them as soon as possible.

“Operation Orbital, our training deployment in Ukraine, has a routine commitment of around 100 personnel – that will fluctuate depending on the type of training taking place.”