Four rhinoceros heads with eight horns worth about 500,000 euro have been stolen from museum storage in Ireland.
Three masked men broke into a facility in Swords, north Dublin, late on Wednesday night and tied up a security man before the robbery, which lasted about an hour.
The raid took place at premises known as the National Museum Archives.
The rhino heads with horns had been taken off public display more than a year ago and put into storage after a spate of similar thefts from museums and private collections in Europe.
"The stolen rhinoceros heads have a total of eight horns that have probably been taken to supply the illegal trade in powdered horn that is used in traditional medicines in the Far East," a spokesman for the museum said.
"Their price is based on weight and the total amount stolen could have a street value in the region of 500,000 euro.
"The National Museum of Ireland took the decision to remove all rhinoceros horn from display and the stolen specimens were placed in storage over a year ago. Currently there are no rhinoceros horns on display in the National Museum of Ireland - Natural History."
Gardai said that the raid took place at about 10.40pm at the building on the Balheary Road and the alarm was raised just before midnight when the tied-up security guard managed to free himself after the gang left. The man was not injured.
The robbers loaded the horns into a large white van. A Garda forensic team has sealed off the premises to carry out a technical examination and an incident room has been set up at Swords Garda station.
Nigel Monaghan, keeper in the natural history division of the museum, said the horns were about 100 years old. The heads and horns were originally trophies dating back to the early 1900s and preserved and mounted by taxidermists.