A Labour MP has compared the actions of Vladimir Putin in Ukraine to those of Adolf Hitler in the 1930s.
The situation in the Ukraine is becoming increasingly fraught with Boris Johnson warning on Monday an invasion by Russian troops could take place within 48 hours.
The prime minister has urged the Russian president to step back from the "edge of a precipice", saying "serious preparations" were being made for a Russian invasion, with around 130,000 troops massed on the borders of Ukraine.
Some have expressed concern that diplomatic efforts could prove in vain if Putin has already decided to invade Ukraine.
He has previously outlined the scale of his ambitions in the region in a controversial essay published last year in which he stated that Russians and Ukrainians were "one people – a single whole".
On Sunday, Chris Bryant, the Labour MP for the Rhondda and a member of the influential foreign affairs committee, drew comparisons between the Russian president and Hitler.
"The real parallel with the 1930s is surely Putin’s argument about Russians and Ukrainians being the same people," he wrote on Twitter. "Which is strongly reminiscent of Hitler’s argument about the Sudeten Germans."
Hitler's annexation of the Sudetenland – the northern part of former Czechoslovakia – in 1938, came after Germany claimed that a majority of the region's population were ethnically German.
With the threat of war looming over the issue, a diplomatic agreement by the British, Italian, French and Czechoslovakia leaders ceded the region to Germany in the Munich Agreement.
However, far from avert war the agreement only served to prolong it and, in March 1939, Hitler reneged on his promise and staked his claim to the rest of Czechoslovakia.
As a result, the Munich Agreement is widely seen as one of the most notable moments of failed appeasement in recent history.
The comparison to Putin can be seen in his previous aggression in Ukraine in March 2014, which led to Russia annexing the Crimean Peninsula.
In an article on the situation in Ukraine last month, the UK defence secretary Ben Wallace dismissed the claims made by Putin in his essay, saying the article was "short on accuracy and long on contradictions".
"Ukraine has been separate from Russia for far longer in its history than it was ever united," he added.
Watch: Minister warns Russian attack 'could be very close'
At the weekend, Wallace also likened last-ditch diplomatic efforts to stop Russian aggression to the appeasement of the 1930s, describing a "whiff of Munich in the air".
He said Russia invading Ukraine was "highly likely", saying: "It may be that he [Putin] just switches off his tanks and we all go home but there is a whiff of Munich in the air from some in the West."
On Monday, armed forces minister James Heappey defended the defence secretary, telling BBC Breakfast that Wallace was referring to the "futility of the diplomatic effort".
"I don’t think for a second that Ben was seeking to draw parallels, either between Hitler and president Putin, nor between Western allies and their approach," he added.
Bryant has been outspoken about the worsening situation with Russia in recent months and years and has criticised the Conservatives for not acting tough on Putin.
On Saturday, he tweeted: "The Tories got the relationship with Russia wrong from the moment Cameron arrived in Downing Street.
"They wanted to do more business with Russia because it was a BRIC [Brazil, Russia, India and China] economy and they wanted to press the reset button.
"Some of us warned that after the murder of Litvinenko this was a fool’s errand because Putin respects strength not compromise. I warned repeatedly about his territorial ambitions and the difficulty for UK businesses trading in manifestly corrupt Russia.
"I fully support the government over Ukraine, but Putin’s territorial aggression has been there for all to see for years. It is infuriating that successive governments since 2010 have vacillated and equivocated, and Putin has interpreted this as weakness.
"We would be in a much better place today, and our tough talk would be much more effective, if the government had taken more robust action on money laundering and dodgy Russian money. Some ministers know this, and have been saying so privately for years."
Watch: What is behind the tensions with Russia?