Russia's invasion of Ukraine has intensified calls for a boost to the UK's defence budget.
Assessing the conflict, UK Chief of Defence Staff, Sir Tony Radakin said Russia had suffered its worst month for casualties since the start of the war in 2022.
He said Russia’s forces suffered an average of about 1,500 dead and injured "every single day" in October.
Russia does not disclose the number of its war dead, but Western defence officials have said October's death toll was the heaviest so far.
Sir Tony said the Russian people were paying an "extraordinary price" for Putin's invasion.
"Russia is about to suffer 700,000 people killed or wounded – the enormous pain and suffering that the Russian nation is having to bear because of Putin’s ambition," said Sir Tony.