The organisers of a major day of prayer for the nation are hoping to mobilise churches and networks across the UK in a season of united prayer and outreach.

The national day of prayer at West Ham football stadium is expected to draw around 20,000 Christians. It is one of several events being held in preparation for a season of 500 days of prayer starting on August 1 and running until December 31, 2011.

The 500 days of prayer are being launched with a view to mobilising churches in prayer ahead of a major prayer gathering at Wembley Stadium planned for 2011 and a year of prayer scheduled for 2012 to coincide with the Olympics in London.

Organisers, Global Day of Prayer London (GDOPLondon), say they want June 13 to be a “catalyst” for a greater commitment to prayer for the nation and outreach in local communities, particularly evangelism.

GDOPLondon convener Dr Jonathan Oloyede said: “This year, prayer and mission are going together. There is a challenge to spread the Gospel after praying. We want people to proclaim the Gospel and introduce Jesus, speak about their faith, tell their story. This is what we should do in addition to, not instead of, acts of kindness.”

A network of churches praying 24/7 has sprung up around London in the last few years. GDOPLondon is inviting churches across the UK to consider taking up at least one full day of prayer each month in an effort to build up a national chain of prayer.

Individual Christians are being asked to set their alarms or mobile phones to noon every day and take one minute to pray the Lord’s Prayer over the UK. Later in the year, GDOPLondon is aiming to train and release around 1,000 youth leaders in sharing the Gospel.

Mr Oloyede said: “We want more churches to be praying churches. The national day of prayer is a catalyst for people to pray more actively for the nation and to get enthused for mission – enthused to tell their story.

“But it’s also a call to action. We want to see more churches organising regular prayer meetings and outreaches despite their busy schedules. They can join together with other Christians in holding local, regional and citywide prayer gatherings and in holding events that point people to the Gospel. Prayer and outreach must be included in our list of priorities.”

The West Ham event has been endorsed by London Mayor Boris Johnson. Christians taking to the stage on the day include Christian MPs David Burrowes, Stephen Timms and Simon Hughes, and X Factor finalist and gospel artist Beverly Trotman. It follows on from a series of prayer events held in all 33 London boroughs as well as a number of towns and cities across the UK on the Global Day of Prayer on Pentecost Sunday last month.