Thieves have smashed display cases and stolen more than a billion dollars worth of treasures and jewels in an audacious raid on a museum in eastern Germany.

Authorities say Monday’s pre-dawn raid on Dresden’s world-renowned Green Vault Museum – which holds treasures from across the globe – might be the world’s biggest since the end of World War II.

Dresden police and museum officials said they were still trying to establish exactly how much was stolen. But thieves got away with at least three sets of early 18th-century Baroque jewellery, intricate diamond and ruby brooches, buttons, buckles and other items.

Local media reported the haul was worth up to 1 billion euros ($1.6 billion) – although Saxony state art collections director Marion Ackermann described the missing items as “priceless”.

“We are shocked by the brutality of the burglary,” she said.

On Tuesday (Australian time) museum officials called the theft as an “unimaginable” loss.

Green Vault director Dirk Syndram stressed the museum’s collections in had “invaluable cultural value” – particularly their completeness.

“Nowhere in any other collection in Europe have jewels or sets of jewels been preserved in this form and quantity,” he said.

“The value is really in the ensemble.”

Authorities at the museum after Monday’s audacious theft. Photo: AAP

Ms Ackermann said the stolen treasures were so unique and identifiable it would be impossible to sell them on the open market.

“It would be a terrible thing,” she said when asked whether the jewellery might be broken up or melted down.

Police said security camera footage at the museum caught two men breaking in through a grilled window. The alarm sounded just before 5am on Monday (local time) and officers were there within minutes. But the burglars had already fled.

Bild newspaper said a nearby electricity junction box had been set on fire before the raid, cutting power to the whole area.

The footage shows two hooded figures entering the room, then smashing open the glass case with an axe.

“In total, the entire crime only took a few minutes,” police said.

They later confirmed that an Audi A6 matching the description of the getaway car was found burned in an underground car park in Dresden.

The treasury of Augustus the Strong of Saxony was established in 1723 and today holds about 4000 objects of gold, precious stones and other materials on display in Dresden’s Royal Palace.

The state governor said the vault contained items collected over many centuries.

“It’s not just the State Art Collections that was robbed, but us Saxons,” Michael Kretschmer tweeted. “One can’t understand the history of Saxony without the Green Vault.”

One of the museum’s most famous and precious treasures, the Dresden Green Diamond, is on loan to the Metropolitan Museum of Art in New York for an exhibit, with other valuable pieces.

The 41-carat green diamond was acquired by Augustus III, the son of Augustus the Strong, in 1742, according to the museum.

The museum has not put a current value on the diamond. But it was bought for 400,000 thalers – by comparison, building Dresden’s lavish Frauenkirche church about the same time cost 288,000 thalers. 

-with AAP