Stewart McDonald warned a full-scale war could make things even worse in a conflict that has already seen 13,000 die, and more than one million internally displaced.
It follows claims by the Russian defence minister Sergei Shoigu that US private military companies have stationed troops in eastern Ukraine for a "provocation using unknown chemical components".
Mr McDonald, the SNP spokesperson for defence and member of the foreign affairs committee, compared the tactic to those used by Russia in Syria where claims of chemical attacks were repeatedly made without proof.
He said: “Russian allegations that US proxies are preparing an attack with chemical weapons are an absurd fabrication taken straight from their Syria playbook – a conflict where the Russian government repeatedly and falsely accused the Syria Civil Defence of using chemical weapons to draw attention away from the deliberate targeting of schools and hospitals by Russian forces.
“Like the boy who cried wolf, the Russian government has only itself to blame for destroying its international reputation.
"Instead of choosing peace and dialogue with Russia’s neighbours, President [Vladimir] Putin is attempting to trap Ukraine behind a New Iron Curtain as he attempts to revive the ghost of the Soviet Union.
“The Russian invasion of Ukraine has already led to over 13,000 deaths and over one million people internally displaced.
"A full-scale ground war could create as many as five million refugees – the largest humanitarian crisis on European soil since the Second World War. The UK Government must be prepared for this.”
Mr Shoigu is an ally of Mr Putin and previously pointed the finger at the US for increased tensions near Russia’s border.
He explained: “The United States is building up its military presence at Russian borders. In the countries of Eastern Europe, American units with a total number of about 8,000 servicemen are deployed on a rotational basis.”
Around 100,000 Russian troops are currently believed to be stationed on the border with Ukraine, despite Russia repeatedly denying it has plans to invade.
The president of Ukraine held a video call with 20 US senators and members of Congress on Friday amid tensions with Russia.