Burglars made off with up to £21,000 worth of antiques including rifles, swords and diamonds from Chippenham Auction Rooms.

But the criminals were not clued up on the Chinese dynasties and left behind some of the most valuable items from the ceramics sale scheduled for the following day.

The sale had to be cancelled after the break-in at the Ivy Road auction house last Friday night – it was the second burglary there in a year.

The offenders, who removed tiles and climbed through the roof, took more than £10,000 worth of gold and silver from the strong room, intended for the auction, including a five-stone diamond ring set in 18ct gold, expected to fetch up to £800.

Police said people should be on the look-out for the items on internet auction sites.

Among the items taken were Victorian rifles with bayonets and cavalry swords, being held for a militaria expert who was due to sell them to gun licence holders. Detective Sergeant Simon Childe, based at Melksham CID, assured the public the guns could not be fired. He said: “They are ornamental, not active firearms.”

And principle auctioneer Richard Edmonds said: “With the old calibre of the guns, you can’t get the bullets for them.”

The intruders took a significant amount of the Chinese Song, Yuan and Ming dynasty ceramics, a special feature of Saturday’s sale. These include a 960-1279 AD Longquan ware carved lotus petal bowl, which could have sold for £500.

The thieves also emptied the till before breaking locks and leaving through the back door.

Mr Edmonds said: “Amazingly the burglars missed some of the best items from this section, which will go into a replacement auction to be held this Saturday.

“It is gut-wrenching when you find out you’ve been broken into.

“We have circulated pictures of all the items taken throughout the industry so if there is an attempt to sell them the police will be notified immediately.”

DS Childe said: “The items taken may be offered for sale on electronic auction sites, so we ask the public to be aware and consider what they are buying.”

Visitors who turned up for the monthly antiques and collectables auction last Saturday were turned away.

But they can now look forward to the rescheduled event this Saturday at 10am.

For more about the auction, call (01249) 444544 or visit www.chippenhamauctionrooms.co.uk

Police want to speak to anyone who attended on Friday to view items and noticed anything suspicious, or who has information about a grey Transit van seen on the Ivy Lane industrial estate at about 8.15pm on Wednesday, November 6.

Anyone with information is asked to call DC Hatch at Melksham CID on 101, or Crimestoppers, on 0800 555 111.