Police in Italy are unconcerned about the daring theft of a Flemish master's painting - because they had replaced it with a fake a month ago.

The painting by Pieter Brueghel the Younger, worth millions, apparently vanished from a church on Wednesday.

Thieves used a hammer to smash open its display case and made off in a car.

Hours later, Italian police revealed they had heard rumours of the planned heist - and installed cameras to catch the thieves in the act.

The painting of the crucifixion had also been replaced with a copy, and the original kept safe and sound, they said.

It all happened in the town of Castelnuovo Magra in Liguria, where the painting of the crucifixion is kept in a side alcove of the Santa Maria Maddalena church.

The surveillance footage of the raid is now being carefully studied and investigators are chasing down those responsible.

Earlier, before the switch was revealed, Mayor Daniele Montebello told Italy's Ansa news agency that the painting was "a work of inestimable value, a hard blow for our community".

On Wednesday night, he revealed he had been in on the ruse, explaining that "today for investigative reasons we could not reveal anything".

He also thanked members of the church for holding their peace - "because some faithful had noticed that the one on display was not the original, but did not reveal the secret".

Pieter Brueghel the Younger was the son of another Flemish artist - Pieter Bruegel the Elder - and is famous for both his own paintings and the copies he made of his father's work.

The Crucifixion is a well-known piece of which several copies exist, with small differences between them - including one in the Museum of Fine Arts in Budapest, Hungary.

All are believed to be variations on an original by Bruegel the Elder - but no original by his hand is known to survive.