It's the macabre mystery which dates back 2,000 years.

Archaeologists have revealed how they have found evidence of a bizarre ritual in a Leicestershire field.

Masses of pig bones were unearthed in Hallaton, near Market Harborough – part of one of the most important Iron Age finds anywhere in Britain.

The sacrificial remains of hundreds of pigs have baffled experts, but they believe it could prove key in helping them understand more about religious rituals 2,000 years ago.

Leicester University's Vicki Score, who has been working on the discovery, said: "What is very intriguing is that the front right legs of all the animals are missing.

"That does suggest a ritual nature to the killing. They are pigs rather than any other animal, so pigs must have had a religious significance."

Coins and relics found on the site at Hallaton, near Market Harborough, have already led historians to rethink the nature of links between Britain and the Roman Empire.

The Hallaton Treasure – some 5,300 coins, jewellery, ingots, silver cups and bowls – goes on show for the first time on Saturday and aims to give an insight into life in Britain 2,000 years ago.

Museum curator Zara Matthews said it was believed the treasure was buried by the Corieltavi tribe who lived in the area before or during the Roman invasion by the Emperor Claudius, who invaded Britain in 43AD.

She said: "It is likely the site was a hilltop shrine.

"It was a site for feasting and sacrifice."

The finds were unearthed in a farmer's field in 2000 by a team of local historians aided by experts from Leicester University.

Vicky said: "Without doubt if it had not been for the care with which the Hallaton Fieldwork Group had conducted their work, this internationally important site could have been pillaged and its story lost for ever.

"As it is we are getting a unique picture of British society before the Roman invasion under Claudius."

Harborough Museum has been revamped in a £900,000 programme to buy, conserve and display the Iron Age hoard.

It was closed a year ago so that high-security display cases could be installed.

Star exhibits will eventually include a ceremonial silver gilt cavalry helmet which is being restored by the British Museum – which will take two years.

Harborough museum project manager Frank Hargrave said: "It is in a very bad state as the iron frame has corroded leaving only the silver gilt.

"It is being conserved a grain of soil at a time."

Visitors will be able to see footage of the conservation being carried out in London on screen at the museum.

A day of historical events in the town has been organised for the reopening. Re-enactment groups will depict the Roman invasion, the English Civil War and the First World War.

Ken Wallace, of the Hallaton Fieldwork Group, who discovered the hoard, said: "It is wonderful to see the finds displayed for people to see. They have done a really good job."