The Archbishop of Canterbury has shared of the harrowing experience of visiting the desolate town of Bor in South Sudan, where at least 6,000 were killed during a bout of extreme violence, and has called for "remorseless, unceasing prayer" for an end to the conflict.

Significant political unrest has plagued South Sudan since its secession from the north in 2011 following two bloody civil wars.

A fresh wave of violence began on 15 December last year in the capital city of Juba as a result of an attempted coup by soldiers loyal to President Salva Kiir's former deputy Riek Machar. The fighting escalated; spreading throughout the country and fracturing it along ethnic lines.

The latest reports from the UN indicate that at least 1.5 million people have been displaced since December and the Office for the Coordination of Humanitarian Affairs (OCHA) reports that a staggering 5 million are currently in need of critical humanitarian assistance.

Justin Welby visited Bor, Jonglei State, in January this year where he says the sheer level of destruction was "overwhelming".

"We stood with bodies at our feet, and the smell of death around us, and we prayed," he shared in a video for the Episcopal News Service.

"The shock of so much destruction, of a town of a quarter of a million looted and destroyed, everyone driven into the bush or across the river, perhaps 6,000 dead, perhaps more...all the women raped, the most atrocious sexual violence, was very overwhelming, very desperate," he said.

"It was shocking not only to us...but even to the South Sudanese, who have seen so much suffering.

"One of the prevailing impressions was of a deep sense of shock that after so many years of war, after the creation of the new nation, that they'd found themselves back where they were."

The Archbishop then urged for increased prayer for the divided nation, declaring that "We must be battering the gates of heaven in prayer; remorseless, unceasing prayer".

"As we pray, our minds and hearts are shaped by the wisdom and power of the Spirit of God, and as we pray we engage with God in the struggle against human evil," he said.

Welby then underlined the importance of providing practical assistance to help those in desperate need by preventing the supply of arms, bringing justice to those who fuel the conflict and offering vital humanitarian aid.

He also drew attention to the integral role of the Church in peace building. "The fact that the Archbishop [Daniel Deng Bul] is himself in charge of the reconciliation effort, and was summoned from a meeting in London urgently to take part in the first face-to-face meeting of the president and the rebel leader speaks volumes as to the centrality of the Church," Welby declared.

"It's the churches that are the most effective networks of support across even frontlines."

Despite the horrific situation in South Sudan, Welby was keen to assert that God is still at work in a nation that has turned upon itself in the most violent and terrible way.

"I see God in everything, in a Church that is mobilised against despair in South Sudan when they could have just rolled over and said 'What can we do?'. On the contrary they are leading the struggle against violence," he said.

"I see God in the extraordinary fact that after half a century of civil war and the hardening that that causes, that we could stand in Bor and see people weeping with compassion because the Spirit of God still moves in love in their hearts."

President Kiir and opposition leader Machar signed a peace deal on 9 May. It follows a failed ceasefire previously agreed on January 23, and has been labelled "a breakthrough for the future of South Sudan" by US Secretary of State John Kerry.

Watch the full interview with Archbishop Welby below: [Warning: contains sensitive images].