That last comment was interpreted as a message about Nord Stream 2, which would run from Russia to Germany under the Baltic Sea and is being proposed by Gazprom, a Russian energy company.

The pipeline, which has been planned for more than a decade, retains the backing of the German leadership but has been criticised by political leaders in the US and the UK.

Critics say it could undermine Ukraine, which remains gripped in civil war, because it currently gets transit fees from existing pipelines which run through the country and could be circumvented.

There are also concerns that the pipeline would increase European reliance on gas from Russia, the prices of which Mr Putin has shown he is willing to manipulate for geopolitical purposes.

Ms Merkel is due to stand down as German Chancellor once coalition talks among German political parties have reached an agreement and a new administration is formed. Olaf Scholz, a Social Democrat, is widely expected to succeed her.

The change in leadership theoretically opens the door to a change in policy on Russian gas, though that remains unclear. Meanwhile, Nord Stream 2 is yet to get its final sign off.

Some European political leaders other than in Germany have been lukewarm about the pipeline in the past. 

Germany will have final sign-off on the project, meaning Mr Johnson’s message could be interpreted as a call for other European nations to apply pressure on Berlin. 

‘Solidarity with our friends in Poland’

Mr Johnson’s reference to tensions at the Polish-Border being “contrived” referred to the thousands of migrants that remain camped on at the Belarus side for a second week.

Polish politicians, and now the Prime Minister, have suggested the stand-off is being orchestrated by Mr Putin and Belarusian dictator Alexander Lukashenko. 

Mr Macron’s warning to Mr Putin on Monday, the hardest line a Western leader has taken in the latest stand-off, reflects the level of concern about the Russian military build-up by Ukraine.

Ms Merkel also spoke with Mr Lukashenko of Belarus for about an hour about the border crisis, according to Belarusian state media.

At a Downing Street press conference on coronavirus the Prime Minister, when asked about the border tensions, expressed “solidarity with our friends in Poland”.

He added: “We would encourage everyone to work for peace and stability in the European region. We stand shoulder-to-shoulder with our friends across the whole region – Estonia, Poland.”