Virgin of Guadalupe - one of Mexico's most revered images

It dates from 1531, when the Virgin Mary is said to have appeared to a Mexican Indian.

According to legend, her image was imprinted on his clothes - which are still preserved in a church in Mexico City.

There are copies in many homes in this devoutly Catholic country.

Protests

So controversy was probably inevitable when a cartoonist did his own version - replacing the image of the Virgin, with a naked Marilyn Monroe.

When the picture was put on display in Guadalajara, the director of the museum resigned in protest.

The arrested men are reported to have told the police that the picture, called "La Patrona", was an insult to Catholics devoted to the Virgin of Guadalupe.

The head of the Roman Catholic Church in Mexico, Cardinal Rivera, has backed their actions, saying it was the artist who was to blame.

The organisers of the exhibition have warned that the protest could herald a new mood of conservatism when the country's new - devoutly Catholic - President, Vicente Fox, takes office later this year.