Former International Development Secretary Andrew Mitchell has drawn parallels between Russia's actions in Syria and that of the Nazis before World War Two.
The Tory MP's comments come ahead of an emergency Commons debate today into the mounting humanitarian crisis in Aleppo.
Former chief whip Mr Mitchell accused Moscow of "shredding the international rules-based system of law" as condemnation grows over its alleged role in the bombing of a UN aid convoy.
Defence Secretary Sir Michael Fallon is among those who have accused Russia of helping the Syrian government in bombing its own people, which it denies.
Mr Mitchell has condemned Russia for its part in the "unfolding humanitarian catastrophe in Aleppo, and more widely across Syria".
Speaking in the Commons on Monday he joined other international political figures in saying Russia was committing a war crime with its use of incendiary weapons and munitions such as cluster bombs in densely populated areas.
He also compared Moscow's actions to that of the Nazis in the Spanish Civil War.
"We are witnessing events which match the behaviour of the Nazi regime in Guernica in Spain.
"Russia is shredding the international rules-based system of law.
"They are destroying the United Nations and its ability to act, in the same way the Germans and the Italians destroyed the League of Nations in the 1930s."
Today's debate is expected to focus on what the UK can do to relieve the the building humanitarian crisis in the rebel-held east Aleppo where 250,000 people are trapped by the regime's barricades around the neighbourhood.
At least 338 people have died as a result of intense shelling in the built-up area where food and medical supplies are running desperately low.