Keir Starmer has accused the Stop The War coalition of siding with Russia as fears grow that it is about to invade Ukraine.
The Labour leader accused the organisation - which has his predecessor Jeremy Corbyn as its vice-president - of consistently supporting the west’s enemies.
His comments, in an article for The Guardian, came as Corbyn addressed a Stop The War rally in London titled “No war in Ukraine - Stop NATO expansion.”
Starmer wrote: “Nobody wants war. At first glance, some on the left may be sympathetic to those siren voices who condemn NATO. But to condemn NATO is to condemn the guarantee of democracy and security it brings, and which our allies in eastern and central Europe are relying on, as the sabre-rattling from Moscow grows ever louder.
“That’s why the likes of the Stop the War coalition are not benign voices for peace. At best they are naive; at worst they actively give succour to authoritarian leaders who directly threaten democracies.
“There is nothing progressive in showing solidarity with the aggressor when our allies need our solidarity and – crucially – our practical assistance, now more than ever. The kneejerk reflex, “Britain, Canada, the United States, France – wrong; their enemies – right”, is unthinking conservatism at its worst.
“To truly stop war, you need to show you are serious about standing up for peace, that you are serious about keeping your promises to your friends, and that you will always stand up to those who threaten.”
The Labour leader added: “Moscow’s hard-line leadership won’t see a rally on the streets of Britain as a reason to pull its tanks from Ukraine’s borders. All it will see is naivety and weakness – virtue signallers in the west providing a smokescreen so it can go on beating up and jailing those brave individuals who dare to stand up to its despotism on the streets of Russia.”
Starmer said that under his leadership, “Labour’s commitment to Nato is unshakable”.
However, in an interview with the BBC during a visit to NATO HQ in Brussels, he was repeatedly asked why he sat on Corbyn’s frontbench as shadow Brexit secretary when he knew the then leader held strong anti-NATO views.
Starmer said: “Jeremy Corbyn and I disagreed on many things. I was leading for our party on the Brexit negotiations, the difficult votes we had in Parliament, and it was very important that we had that lead at the time, that were very difficult, seems a long time ago.
“Very difficult discussions and decisions at the time, but does it mean I agree with Jeremy Corbyn on everything? Of course it doesn’t. He was leader of the party and I was leading on the Brexit negotiations.”