Evgeny Buzhinsky – who served in the Russian military for more than 40 years – said the row between Britain and Putin was creating a situation “worse than the Cold War”.
Buzhinsky told the BBC the expelling of diplomats by both countries over the poisoning of Sergei Skripal and his daughter Yulia in Salisbury could lead to war.
Buzhinsky said that Britain and Russia were heading for “a real war”.
He said: “Worse than the Cold War is a real war.
“It will be the last war in the history of mankind.”
Skripal and his daughter have been in hospital since ingesting the deadly nerve agent novichok in Salisbury, Wilts on March 4.
Buzhinsky was asked if the poisoning of Skripal could lead directly to war. He responded: “Not the Salisbury poisoning, but the pressure.
And he warned that the row was only going to escalate further.
“You expel diplomats, we expel diplomats, you further expel, what’s the next step? It’s a breach of diplomatic relations.