UK defence minister James Heappey has said there will be no British troops in Ukraine in the case of an invasion, adding that Russia could invade “at no notice”.

British personnel have been in Ukraine on a training mission codenamed Operation Orbital over the past decade, whereas others have been deployed there recently to train the Ukrainian military on anti-tank missiles.

The order to return comes as all British nationals in Ukraine have been advised to leave as soon as possible. Advice was updated advice last night to say UK nationals should “leave now while commercial means are still available”. Australia, Canada, Japan and the Netherlands are among those issuing similar advice.

Those who remain, Mr Heappey has clarified, should not expect an Afghanistan-style military evacuation.

Mr Heappey’s comments echo those of US National Security Adviser, Jake Sullivan, who warned on Friday that an invasion could be “imminent”. Mr Sullivan added: Russian forces were now “in a position to be able to mount a major military action”.

“Simply put, we continue to see very troubling signs of Russian escalation, including new forces arriving at the Ukrainian border”.

The remarks mark a clear escalation in the urgency of warnings from US and UK officials.

Conversely, Moscow has accused Western countries of stirring up hysteria. Russia’s foreign intelligence chief Sergei Naryshkin has condemned “dangerous lies” being spread by the US and in Western capitals.

But rhetoric from Moscow is hardening; and six Russian warships have reached the Black Sea with more Russian military equipment arriving from Belarus, north of Ukraine.

This week, Russia launched joint military exercises in neighbouring Belarus and naval drills in the Black Sea.

Over 100,000 Russian troops are currently massed on the Ukrainian border as attempts to de-escalate tensions through diplomacy continue. Both US President Joe Biden and France’s President Emmanuel Macron are due to speak to Russia’s Vladimir Putin by phone.

The US secretary of state, Anthony Blinken, said Washinton was prepared for either diplomacy or “aggression” from Moscow, ahead of his expected call with Russia’s foreign minister.

On Friday, President Biden hosted a video call with transatlantic leaders in which they agreed on coordinated action to inflict severe economic consequences on Russia if it invaded Ukraine.

Prime minister Boris Johnson told allies that he feared for the security of Europe in the virtual meeting. The prime minister’s office said: “He impressed the need for Nato allies to make absolutely clear that there will be a heavy package of economic sanctions ready to go, should Russia make the devastating and destructive decision to invade Ukraine”.