Crown jewels belonging to the Swedish Royal Family were stolen yesterday by thieves who sped away on a speedboat.

Police were seen chasing the two suspects on a motorboat after the 'priceless' items were taken from Strängnäs Cathedral in southeastern Sweden.

Two royal crowns - one belonging to King Karl IX, the other to Queen Kristina - were taken, as well as a royal orb.

Two royal crowns - one belonging to King Karl IX, the other to Queen Kristina - were taken, as well as a royal orb

Karl IX was the King of Sweden from 1604 until his death in 1611. The two crowns are the burial crowns from 1611 but were later exhumed and put on display.

Both crowns are made of gold and inset with pearls and other precious stones.

Christofer Lundgren, dean of the cathedral, said: 'This is part of the national cultural heritage - this is a theft from Swedish society.'

The cathedral was open to the public when the jewels were stolen from locked-up glass boxes.

Police spokesman Thomas Agnevik last night said there had been no arrests. He said: 'It's 1-0 to them right now.'

Two men were seen jumping into a motorboat outside the cathedral (pictured), which is about 50 miles from Stockholm, after the theft

He added: 'I have talked to someone at the county administrative board that says it is not possible to put an economic value on them - these are invaluable objects of national interest.

'We are looking for a small and open motorboat.

'We have some different information about how exactly the boat looked. We are now examining all the tips we receive.'

He added: 'By boat you can reach Mälaren, Köping or Arboga in the west, or Västerås, Eskilstuna or Stockholm if you drive east.

'We direct our search in all these directions.'

Eyewitness Tom Rowsell, who is getting married at the cathedral this weekend, described the incident.

He said: 'One of my friends saw two people running...I saw the boat just there, a white little boat with a motor on the back.

'The two men hurriedly jumped on board. We contacted the police and told them and they told us they had taken something from the Cathedral.

'I knew immediately they were burglars because of the way they were behaving.

'The girls said it was odd, in this small quiet town...but the fact that the boat was waiting, it was obvious to me that they were burglars.

The cathedral was open to the public when the jewels were stolen, Aftonbladet reported. Pictured left: The grave of Karl IX at the cathedral. Right: The king himself

'I think it's awful, it's despicable that people would steal from a holy building and take something of historic and monetary value. I hope the police succeed in finding them.'

Nobody was hurt during the raid.

It is not the first time the Swedish Royal jewels have been stolen.

In 2012, a 19-year-old man admitted stealing 850,000 kronor (£102,000) worth of jewels from Princess Christina's apartment near the Royal Palace.

He allegedly sold most of the jewels to two drug dealers and also reportedly threw a tiara off a bridge in Stockholm.