The Archbishop of Canterbury says he has been struck by the "magnitude of evil" unleashed in Ukraine after paying a sombre visit to a mass grave in the war-ravaged country.
Archbishop Justin Welby prayed at the spot where 116 bodies are buried in Bucha, on the outskirts of Kyiv.
He also visited a "deeply emotional" photo exhibition displaying pictures of murdered civilians and showing the communities' response in burying the dead.
The photo exhibition was on display inside St Andrew's Greek Catholic Church in Bucha, where the Archbishop met and prayed with its priest, Father Andriy Halavin.
In Irpin, the Archbishop visited the 'Bridge of Hope' - the name given to a make-shift bridge that was the only route out of the occupied city and neighbouring Bucha.
Local priests told of their efforts to help people escape across the bridge under Russian fire. The Archbishop then prayed at the bridge, which is marked with wooden crosses in memory of those who fell trying to cross over.
Archbishop Welby has spent three days in the country meeting church leaders and locals in an act of solidarity.
He condemned the Russian invasion of Ukraine and said it had put the people of Ukraine through "hell".
"Russia's invasion of Ukraine is an act of evil. Being in Irpin and Bucha today has made my conviction of that even stronger. War unleashes the forces of hell and today I met people who have been through that hell," he said.
"So often in places of war and conflict, the church suffers alongside the communities it serves.
"Today I met heroic priests, seminarians and local Christians who – even amidst their own agonising suffering through this brutal invasion – have loved, cared for and supported those around them.
"I feel today that I have touched the hem of Jesus' cloak and seen his face in the faces of the people of Irpin and Bucha."
The Archbishop heard further accounts of the horrors of the invasion from Ivan Rusyn, a Baptist minister and president of the Ukrainian Evangelical Theological Seminary (UETS), which was bombed in March, a few days after he and his staff were evacuated.
Welby said it was "a great honour" to spend time with the seminary's faculty and students.
"I give thanks to God for their courageous faithfulness to Jesus Christ. They will remain in my prayers for a very long time – as will all the people of Ukraine," he said.
Reflecting on his visit, the Archbishop asked Christians to pray for Ukraine and its people this Advent.
"It has been a profound privilege to visit Ukraine," he said.
"This visit has made me even more determined to stand in solidarity with the heroic people of this country. I have been so struck by the bravery, resilience and faith of the people I have met.
"But I have been struck too by the magnitude of evil that has been unleashed by this unjust invasion – which means that our resolve to stand with Ukrainians in their struggle for freedom must be even greater.
"I appeal to the Church of England, the Anglican Communion and Christians around the world to pray for Ukraine this Advent – and for all people around the globe living through conflicts and injustices."