BORIS Johnson has said a newly-commissioned nuclear submarine is a “guarantor of peace” rather than a “weapon of war”.

Making a speech at the commissioning of HMS Anson, the Prime Minister said in an uncertain world the UK needed a guarantee of peace more than ever.

Johnson and other ministers attended a commissioning ceremony for the new Astute-Class nuclear-powered attack submarine, in Barrow-in-Furness, Cumbria.

The UK and Australia are deepening defence ties and have entered into the trilateral Aukus partnership with the US.

READ MORE: CND Fringe film shows dangers of UK's Trident nuclear weapons at Pianodrome in Edinburgh

The agreement will see the UK and US help Canberra to develop its own nuclear-powered submarines.

Speaking at the commissioning ceremony, the outgoing PM told reporters: “What we are looking at is the policemen of the world, gathering intelligence, protecting our sea lanes, cruising up behind you silently, you do not even know it’s there, and invisibly helping to create that forcefield around us that is warding off attack on Nato countries for 80 years, or getting on for 80 years, keeping safe a billion people around the world. That is what this machine does.

“That’s why I’m so pleased, by the way, but under the Aukus agreements with Australia and with the United States, the technology we hope in the submarine will be used to help keep people safe across the whole of the Pacific region as well.

“Now, some people will continue to insist that this is a weapon of war. I tell you that she is a guarantor of peace. And, in this uncertain world, we need that guarantee more than ever.

“I congratulate all those who designed her. All those who built her. And I know that in the decades to come, all those who are going to set to sea in her.

“I know that in decades to come, when she’s out at sea, unseen beneath the surface of the water, keeping us safe, we will all remember the day that we were here in Barrow to see HMS Anson commissioned.”

Scottish Green MSP Ross Greer said the weapons Johnson is praising are "incompatible with human rights".

“Nuclear weapons are devices of indiscriminate slaughter," he said. "Even one of the warheads that Boris Johnson has called a 'guarantor of peace' would do terrible damage and kill at least hundreds of thousands of people.

"They are totally incompatible with a human rights-based foreign policy and will have no place in an independent Scotland.

"Putin’s brutal invasion of Ukraine emphasises the terrible threat posed by these weapons, and the need to push for global disarmament. Never again should anyone have to experience the horrors that the people of Hiroshima and Nagasaki went through."

Greer said instead of spending more than £2 billion pounds renewing Britain's nuclear weapons, Westminster should be investing that money in helping people through the cost of living crisis.

He said: "A tiny fraction of that sum would easily help families pay their fuel bills and deliver a comprehensive home energy efficiency programme, reducing the need to turn on the heating this winter in the first place.

READ MORE: How Faslane Peace Camp activists are reacting to the Tories' nuclear power push

"The best thing that this generation of political leaders could do for peace is ensure that we finally eliminate nuclear weapons for good.

"Next year’s referendum will give us the chance to get these abhorrent weapons out of Scotland. But it’s not just Scotland that we want to see scrapping nuclear weapons. It is all governments who possess them.

"The UK renewing rather than reducing its own nuclear arsenal just perpetuates nuclear escalation.

"I look forward to the day when an independent Scotland can join the 66 nations, including our closest neighbours in Ireland, which have already signed the UN treaty to ban nuclear weapons."