Churches across the UK and Ireland are uniting in prayer for Ukraine on Sunday afternoon.
Dr John Sentamu, Chair of Christian Aid and former Archbishop of York, will be taking part in an act of witness outside the Ukrainian embassy in London on Sunday.
The vigil, at 2pm, has been organised by Christian Aid and will also be joined by Kenneth Nowakowski, Bishop of the Ukrainian Catholic Eparchy of the Holy Family of London, Archbishop Nikitas, Greek Orthodox Archbishop of Great Britain, and Joanne Grenfell, Anglican Bishop of Stepney.
They will come together to pray for the people of Ukraine and an end to the conflict.
On Saturday evening, Christian Aid projected a graphic of the Ukrainian flag onto Westminster Abbey and the Methodist Central Hall.
The graphic featured a message encouraging people to unite in prayer for Ukraine.
Dr Sentamu said: "Like the people of Ukraine looking out for their neighbours or the charity workers delivering emergency food to people seeking refuge, we must bring hope.
"That is why Christians from across the UK and Ireland - recognising the God-given human dignity and rights of every human being - are uniting in an act of witness to pray for Ukraine and an end to the conflict.
"With one voice, we are uniting behind a simple message: immediately agree to a ceasefire and unequivocally commit to protect civilians and key services.
"Every prayer, every gift, every action brings hope to the people of Ukraine. By joining us, you can give hope to our brothers and sisters in Ukraine."
The Moderator of the Church of Scotland General Assembly, Jim Wallace, said the vigil was an opportunity to renew calls for a ceasefire.
"Watching regular news reports of the tragic and violent events in Ukraine, it would be all too easy to feel helpless. But, as followers of Jesus, we cannot ignore the plight of the Ukrainian people," he said.
"Our response must be rooted in prayer, not least so that those who suffer and are in fear might know they are not forgotten and most certainly not forgotten by God."
He added, "I hope that Christians in every corner of the land will take this opportunity to display solidarity with our brothers and sisters in Ukraine."
The vigil has been endorsed by the Archbishop of Canterbury, Justin Welby.
"I urge all Christians to come together on the 3rd of April to pray and light candles for the people and the peace of Ukraine: to pray for hope for those fearful of the future, to pray for God's comfort for those suffering, and to pray for the Holy Spirit to turn hearts towards the compassion and justice that the resurrected Christ promises us will eventually prevail," he said.
