State prosecutors in an Italian town have dropped an obscenity investigation into the blockbuster movie The Da Vinci Code, a day after it was launched.

The port village of Civitavecchia, north of Rome, was the centre of international media attention over the investigation.

But the state prosecutor's office in the town said the decision to drop a plan to lay charges was made based on the merits of the case.

"There are no grounds for this investigation," an official said.

It was launched following a complaint from a group of clergy who claimed the film violated Italian obscenity laws because it puts forward the idea that Jesus married and had a child.

It named 10 people associated with the film, including director Ron Howard and Dan Brown, author of the bestselling novel.