Followers of St Padre Pio, Italy's best loved saint, are up in arms over a plan to move his relics from the crypt of the church where he is buried in southern Italy to a nearby modern church designed by the Italian architect Renzo Piano.

A Padre Pio website run by Francesco Traversi, a Turin lawyer, said "Padre Pio must not be touched". Mr Traversi said he had written to Pope Benedict XVI to say that to exhume the remains of a saint would amount to "sacrilege". The transfer of the remains requires the permission of the Holy See.

Mr Traversi said the proposal to move the remains was "persecution post-mortem", and warned the Vatican it was risking a "popular revolt". However Father Antonio Belpiede, spokesman for the Capuchin friars who run the Padre Pio sanctuary at San Giovanni Rotondo, said the space in the crypt at the church of Santa Maria dell Grazie where the saint's remains were entombed was "wholly inadequate" for the millions of pilgrims who come to pay homage to him.

He said exhumation was not sacrilegous but was in accordance with Canon Law, and the remains of St Francis, St Clare and St Antony of Padua had been moved. The most likely date in Padre Pio's case was next September, the fortieth anniversary of his death. Seven million people a year visit the saints tomb at San Giovanni Rotondo, which generates a huge income as a result.

However Father Luigi Villa, editor of the review "Chiesa Viva" (Living Church) said Piano's new 9000 square metre church at San Giovanni Rotondo, inaugurated in 2004, had unacceptable "Masonic symbolism", such as a triangular shaped prayer hall.

Francesco Forgione (1887 -1968), canonised as Saint Pio of Pietrelcina, was given the name Pio when he joined the Order of Friars Minor Capuchin. Even when young he was said to experience heavenly visions and ecstasies.

In 1916 Padre Pio moved to San Giovanni Rotondo, where he stayed until his death. Two years later he received the Visible Stigmata, the five wounds of Christ, which he retained for the rest of his life. But as his fame grew and pilgrims flocked to see him the Vatican began investigating accusations of immorality and fraud.

Last month the Italian historian Sergio Luzzatto revived the theory that Padre Pio had faked his stigmata by using carbolic acid to self-inflict the wounds. However in his lifetime Padre Pio acquired millions of devotees, and Pope Paul VI later dismissed all accusations against him. His funeral was attended by over 100,000 people, and he was canonised by Pope John Paul II in 2002.

Last month the 71-year-old mother of a former Orthodox priest in Romania claimed she had been cured of lung cancer through the intercession of Padre Pio, and said all members of her parish had converted to Catholicism as a result.