A UK atheist group has launched an advertising campaign on public transport across Britain.

The ad, which says: “There’s probably no God. Now stop worrying and enjoy your life”, is appearing on 600 buses in cities across England, Scotland and Wales.

It is set to appear on an additional 200 ‘bendy’ buses in London for a month. Two large LCD screens bearing the atheist message have been placed in Oxford Street.

Meanwhile, 1,000 posters bearing quotes from well-known atheists will be placed in London Underground trains for two weeks starting on Monday.

Last August an initial attempt to raise funds via online donations failed to attract sufficient support.

However, a high-profile media campaign supported by celebrity atheists like Prof. Richard Dawkins led to the campaign raising more than £140,000.

The use of the word ‘probably’ in the slogan, “there’s probably no God”, has surprised some, but is was thought that a categorical denial of God’s existence could break advertising rules.

Prof. Dawkins, author of The God Delusion, said: “I wanted something stronger but with hindsight I think it’s probably a good thing because it makes people think.

“It’s just food for thought – people will have conversations in pubs when they see these buses.”

A Church of England spokesman said: “We would defend the right of any group representing a religious or philosophical position to be able to promote that view through appropriate channels.

“However, Christian belief is not about worrying or not enjoying life.”