A major defence review should prepare the UK to “wage peace” to help save lives, taxpayers’ cash and control migration, according to the Archbishop of Canterbury.

The Most Rev Justin Welby said the new Government’s root and branch review needs to develop a “peace-building option”, alongside preparedness for war, in a bid to stop conflict before it happens.

He explained this could enable the UK to extend its influence, protect its interests and “guard against fresh waves of migration”.

Speaking during a debate on Sudan, Mr Welby said he had heard reports from those meeting small boats crossing the Channel of a “very high proportion” of people arriving from the war-torn African country.

Sudan descended into conflict in April 2023 after months of worsening tensions turned into open fighting between rival factions, including the Rapid Support Forces (RSF) and Sudanese Armed Forces (SAF), seeking control of the country.

Mr Welby described Sudan as a “human catastrophe on an extraordinary scale” and said the use of “vast quantities” of humanitarian aid only results in temporary solutions.

He acknowledged the “hard work” of the Foreign Office in response to Sudan, before highlighting the UK Government’s desire for a return to democratic civilian-rule.

Mr Welby told the Lords: “But as we’ve seen elsewhere, peace with an authoritarian government is better than no peace at all, and I hope that is not so much of a red line that we will not work to establish the ceasefire and the stability which will enable civilians to take over.”

Mr Welby raised the need to “wage peace” and highlighted the strategic defence review (SDR) as an “important and welcome opportunity” to build a new “pillar” in the way the UK structures its defence and security operations.

He said: “It was a pillar notably absent from the two integrated reviews. A peace-building option, well developed and acting in areas of fragility, would extend our influence, protect our interests and, as has been said several times, guard against fresh waves of migration.

“I already hear anecdotally from within the diocese I serve and its south coast, that of Canterbury, that those who are meeting those landing in boats find a very high proportion indeed are coming from Sudan.”

Mr Welby suggested the UK needs to invest longer-term in “broader reconciliation resources”, saying: “Specifically designed with partners to find peaceful solutions.

“In other words, the SDR should be full spectrum, preparing this nation not only to wage war but to wage peace as well. I fear that may not be the case.”

Mr Welby said he hopes the Foreign Office will look “very carefully” at putting such mechanisms in place, adding: “Not least, in our current times in this country, for reasons of economy.

“Stopping conflict before it happens via peaceful, political solutions should be central to any security and defence root and branch redesign.”

Mr Welby pointed to the UK’s “enormous” influence and expertise in sub-Saharan Africa, adding: “The work of peacebuilding not only saves lives, it saves vast amounts of taxpayers’ money for defence, for migration control and from humanitarian aid.

“It can be used expertly in contexts where our military would never operate in force, and rightly, and yet where strategic foreign policy must work, such as in the context of securing critical minerals for the global transition to renewable energy, like the DRC (Democratic Republic of the Congo).

“Reducing the need for emergency funding, reducing destruction and reducing the dangers of vastly increased immigration are in our interests.”

Mr Welby said the Foreign Office’s “negotiation and peace process support team” is “underfunded” and “understaffed”, as he proposed creating a broader joint reconciliation unit.

Opening the debate, Foreign Office minister Lord Collins of Highbury warned the “world is not paying enough attention” to Sudan.

He said: “Sudan is facing a manmade famine and one of the worst humanitarian crises in the world.

“More than 10 million people have been forced to leave their homes, and recent widespread flooding has pushed the country to the brink, devastating an extremely fragile ecosystem.

“The UN estimates that more than 24 million people – about half the Sudanese population – need humanitarian assistance, a figure, sadly, that continues to grow as the conflict drags on.”

Lord Collins said the UK has increased its humanitarian support to Sudan and sanctions have been imposed on key figures linked to both sides of the conflict.

He added: “Turning to peacebuilding, the United Kingdom supports the establishment of a civilian-led government in Sudan. This country’s future must not include those who have led it into turmoil.”

Lord Collins went on to condemn “atrocities” being committed in Sudan, saying: “Some attacks by the RSF and its allied militia appear to have been ethnically motivated, and these bear all the hallmarks of ethnic cleansing.

“Meanwhile, the SAF have launched indiscriminate air strikes in heavily populated areas, with no regard for civilian casualties.”

Conservative former minister Baroness Anelay of St Johns said Sudan “threatens to be deadlier” than either conflict in Gaza and Ukraine.