Priceless artefacts from a Napoleon Bonaparte collection have been stolen from a museum on the Mornington Peninsula in Victoria.

Burglars broke into The Briars, a historic homestead at Mount Martha on Thursday night and tripped an alarm.

Police believed the thieves had gained access through a bathroom window.

Museum coordinator Steve York says the collection was put together by the Balcombe family who were close friends of the French emperor.

Mr York says 10 items were taken from the collection, including locks of Napoleon’s hair and a silver inkwell set with three gold Napoleons which were allegedly in his pocket when he died.

Some miniature portraits of Napoleon and Josephine were also taken.

“Really they’re priceless because they can’t be replaced. We’re quite distraught. Irreplaceable,” Mr York said.

“We’ve now relocated the rest of the collection.

“This has proved it’s vulnerable and so it’s now being relocated to secure it until we look into improving the physical security in the future.”

Detective Senior Sergeant Michael Lamb says security guards were on the scene within 10 minutes of the alarm going off and the offenders were gone.

“We think this was a fairly targeted theft,” he said.

“They will be very difficult to dispose of publicly so we’re asking for anybody who has been approached by anyone with these rare artefacts looking to sell them to contact Crime Stoppers.”

Detective Senior Sergeant Lam says it was a well-planned operation.

“We think they knew what they were looking for,” he said.

“We think its probably destined for a private collection. It could well be stolen to order.”

The collection was put together by Dame Mable Brooks, the grand-daughter of Alexander Balcombe.

“Alexander Balcombe settled here [in Australia] in 1846 and sat on Napoleon’s knee as a little boy,” Mr York said.

“The family were good friends with the emperor when he was sent into exile on St Helena.”

Mr York says the collection has become very popular since the Napoleon exhibition at the National Gallery of Victoria last year.