Pope John Paul II is believed to be preparing an onslaught on new age beliefs in time for the millennium.

He is expected to set out his thinking in an encyclical - a letter sent to all Roman Catholic bishops - the most authoritative way in which he can make known his ideas.A systematic critique is to be made ready for publication later this year, say reports in Rome. Experts have produced working papers on individual topics, the conclusions of which will be considered for inclusion in the pope's work.

His attack is expected to be set in the context of an offensive against modern philosophical trends. His main objection is understood to be the concept of "systematic doubt" on the grounds that it precludes a belief in God rooted in certainty.

The pope sees systematic doubt as the key to a system of beliefs that puts man, not God, at the center of the universe. He is thought to regard the new age movement, with its emphasis on self-realization, as a product of such thinking.

"The pope would oppose anything which suggests that salvation can come from our own works rather than through Jesus Christ," said the Rev. David Evans, secretary to the Catholic Bishops' Conference on Faith and Culture in England.

If, as reports from Rome suggest, a rare encyclical is issued, it will be a measure of the alarm new age thinking provokes at the highest levels in the church.

Cardinal Joseph Ratzinger, the most influential theologian in the Vatican, has dismissed Buddhism, a major influence on the new age movement, as "spiritual auto-eroticism." He claims that it is now Buddhism, rather than Marxism, that poses the true challenge to the church.

Evans argues that the church cannot afford only to condemn. "The church also needs to listen to what the new age has to say. Its rich understanding of humanity stresses the importance of the emotional life and desires which young people find helpful."

The new age movement is an amorphous collection of spiritual ideas ranging from wicca, shamanism and neo-paganism to the human potential movement and astrology.