Dawkins and Christopher Hitchens, the atheist author, have asked human rights lawyers to produce a case for charging Pope Benedict XVI over his alleged cover-up of sexual abuse in the Catholic church.
The pair believe they can exploit the same legal principle used to arrest Augusto Pinochet, the late Chilean dictator, when he visited Britain in 1998.
The Pope was embroiled in new controversy this weekend over a letter he signed arguing that the “good of the universal church” should be considered against the defrocking of an American priest who committed sex offences against two boys. It was dated 1985, when he was in charge of the Congregation for the Doctrine of the Faith, which deals with sex abuse cases.
Benedict will be in Britain between September 16 and 19, visiting London, Glasgow and Coventry, where he will beatify Cardinal John Henry Newman, the 19th-century theologian.
Dawkins and Hitchens believe the Pope would be unable to claim diplomatic immunity from arrest because, although his tour is categorised as a state visit, he is not the head of a state recognised by the United Nations.
They have commissioned the barrister Geoffrey Robertson and Mark Stephens, a solicitor, to present a justification for legal action.
The lawyers believe they can ask the Crown Prosecution Service to initiate criminal proceedings against the Pope, launch their own civil action against him or refer his case to the International Criminal Court.
Dawkins, author of The God Delusion, said: “This is a man whose first instinct when his priests are caught with their pants down is to cover up the scandal and damn the young victims to silence.”
Hitchens, author of God Is Not Great, said: “This man is not above or outside the law. The institutionalised concealment of child rape is a crime under any law and demands not private ceremonies of repentance or church-funded payoffs, but justice and punishment.”
Last year pro-Palestinian activists persuaded a British judge to issue an arrest warrant for Tzipi Livni, the Israeli politician, for offences allegedly committed during the 2008-09 conflict in Gaza. The warrant was withdrawn after Livni cancelled her planned trip to the UK.
“There is every possibility of legal action against the Pope occurring,” said Stephens. “Geoffrey and I have both come to the view that the Vatican is not actually a state in international law. It is not recognised by the UN, it does not have borders that are policed and its relations are not of a full diplomatic nature.”