The Vatican will Tuesday try to revamp the image of Satan, arguing that it needs a "more subtle and sophisticated" definition of evil for the millennium, the London Times reports.

A new formula, formed by a Vatican panel of experts, substitutes "psychological disturbance" for references to the Devil as the embodiment of evil.

"In revising the form of words for exorcism, we have re-thought the nature of the evil we are trying to root out," one member of the commission tells the Times.

Officials say the Church isn't revising "scriptural references" to the Devil or suggesting that people should cease believing in "the Evil One." But priests conducting exorcisms should deal with evil as a force "lurking within all individuals" instead of one that threatens people from without.

Definitions of "demonic possession" and the rituals for dealing with it have remained little changed since Pope Paul V issued the Rituale Romanum in 1614.

Monsignor Corrado Balducci, the Vatican's chief exorcist, says the Church has to adapt to modern thinking and "be more careful in distinguishing between possession by evil spirits and what are more commonly called psychiatric disturbances."

According to Vatican officials, priests will be encouraged not to refer any longer to the Prince of Darkness, the Accursed Dragon, the Foul Spirit, the Satanic Power or the Master of Deceit. Instead the formulas refer to "the cause of evil."

Both Old and New Testaments refer to Beelzebub, the Evil One, or Satan, with the Devil often depicted as Lucifer, a rebel angel expelled from Heaven. The Revelation of St. John (xii.7) describes "war in Heaven between the angels," and "the Dragon, that ancient serpent who led the whole world astray whose name is the Devil, or Satan."

Jesus cast out demons in several famous New Testament passages; St. Mark and St. Matthew both record that Jesus was "tempted by Satan" during his 40 days and 40 nights in the wilderness.

But some modern theologians regard the depiction of Satan as a reptilian beast with cloven hooves, wings and a tail, as a medieval invention, and prefer St. Augustine's definition of evil as "the absence of good".