The Unification Church has asked followers around the world to pray and fast for its founder, the Rev Sun Myung Moon, who is unconscious in intensive care in a South Korean hospital.

The chances of Rev Moon surviving the pneumonia he is being treated for in Seoul in the next couple of days are "50-50", the church said on its website, citing an unnamed doctor caring for the 92-year-old.

Rev Moon's church has gained fame around the world since he founded it in Seoul in 1954, notably for its mass weddings. Rev Moon is a self-proclaimed messiah who said that he was 15 when Jesus Christ personally called on him to complete his unfinished work.

The church also runs a multibillion-dollar religious and business empire which includes The Washington Times newspaper and the New Yorker Hotel in Manhattan.

Church officials say there are millions of members worldwide, but defectors and critics say the figure is no more than 100,000.

Today, the church called for 40 days of prayer and a three-day fast aimed at inspiring Rev Moon's recovery.

His youngest son, Hyung Jin Moon, wrote in a separate message that the family is by his bedside. Rev Moon was admitted to hospital for complications that arose from an "untimely" cold and pneumonia, his son said.

The Rev Joshua Cotter, vice president of the Unification Church USA, said yesterday that the church founder entered the hospital on August 13 and was in a critical condition.

Rev Moon's last major public appearance came last month when he took part in the opening and closing ceremonies of the Peace Cup soccer tournament sponsored by his church in South Korea.