Christian leaders across the UK have encouraged believers of all denominations to join in the Week of Prayer for Christian Unity.

The annual event, which runs from uns from January 18-25, has been observed since 1908. Originally the inspiration of a Catholic priest, Fr Paul Wattson, it is now marked by many denominations.

In a letter of support, the church leaders – including Archbishop Justin Welby, the Archbishop of Canterbury, Cardinal Archbishop Vincent Nichols, Rev Michaela Youngson, President of the Methodist Conference, Archbishop Angaelos, the Coptic Archbishop of London and Pastor Agu Irukwu, Chair of Redeemed Christian Church of God UK, invite Christians to participate in the call to prayer with the 'utmost seriousness'.

The letter urges Christians to 'pray together for Christian unity, in our life together, our witness and our longing to see the Kingdom of God in the midst of our world' and to 'find ways to give expression to our search for greater unity in obedience to the command of Christ that we love one another,' citing Jesus's last prayer on unity taken from John 17.

The church leaders also encourage Christians not just to pray during the Week of Prayer for Christian Unity but also to get involved in Thy Kingdom Come – a global ecumenical prayer movement in which Christians pray for more people to become followers of Jesus Christ. It takes place between Ascension to Pentecost which this year is May 30-June 9.

The Archbishop of Canterbury said: 'Unity in truth and faithfulness in witness are gifts to the Church from the heart of God. Each requires the other. Please join with us and other faithful servants of Christ in churches across England as we pray for the Holy Spirit to work in us to fulfil God's purpose.'

Rev Lynn Green, general secretary of the Baptist Union of Great Britain, said: 'As I meet churches and leaders across Baptists Together it is very clear to me that God is at work stirring up a renewed passion for prayer and a fresh desire to work together because we long to see God's Kingdom come in our communities and nations. Pray, deepen relationships and be part of what God is doing in these days!'