Ancient "halls of the dead" pre-dating Stonehenge are being heralded by archaeologists as the first monuments of their kind to be found in the UK.

The two earth long barrows were uncovered on top of Dorstone Hill in Herefordshire and are thought to date to about 3,800BC, according to Professor Julian Thomas, of the University of Manchester - almost 1,000 years before the famous stone circle in Wiltshire was built.

Archaeologists who have spent a month excavating the mounds say they have removed fine examples of flint weapons and tools, thought to have been buried in the barrows when first created or later left as offerings to the dead.

Prof Thomas said that the site was the only one of its type in the UK where "the halls of the living became the halls of the dead", with the long communal halls first "ritually" burned and then covered over with soil and turf to form the large barrows.

He said: "With this phenomenon of deliberately burning down buildings, tending the fire over a period of days, the argument is that you burn these down when the head of the family dies.

"Here, no new house has been built, but instead they have shovelled up the remains into these barrows and enclosed them with turf.

He added: "It's a very important site."

Among the finds are two stone axe-heads, a flint hand knife and an arrowhead, with some of the raw materials used in their construction pointing to origins hundreds of miles away from where they were found, according to the dig team.

The barrows themselves date to the early Neolithic period when the ancient Britons were starting to settle into small communities.

In one possible clue to the violence of the period, a broken flint arrowhead was discovered in a stone burial chamber uncovered off the side of one of the barrows - although the human remains of the arrow's possible victim which would have lain within the cairn have long since disappeared due to the acidity of the soil, Prof Thomas said.

Archaeologists have also been excited by the level of preservation in the timber construction of the original hall buildings, with the intense heat of the fire carbonising the wood's form even, including the joints and post holes.

The barrows measure 30 metres and 70 metres in length, with a single main burial chamber at each end.

Although made originally of earth, at a later date they were covered in stone like cairns found in the Black Mountains of Wales, Prof Thomas said.

The smaller of the barrows has the remains of holes, thought to have contained two metre-wide upright oak posts between which was supported a trough lined with planks upon which the human remains would be placed.

The dig has been carried out by a team from the Manchester university, the University of Kyushu and Herefordshire Council, who will return to the site to continue work next year.

Dr Keith Ray, Herefordshire county archaeologist and dig co-director, said: "In the British context, the Dorstone find is unique and unprecedented."

Prof Thomas said they had uncovered a picture of a "monument that keeps changing" with the needs of the people living around it at the time.

He added: "This is a special place with significance as new bodies and new offerings are deposited here.

"Hundreds of years after the first burial, there are very fine flint objects being left here.

"It's a very important site, firstly because for the first time we have the fabric of an early Neolithic hall being incorporated into the building of a funerary monument.

"Also, because of the preservation of the remains of the structure including evidence of carpentry, we are going to be able to say rather more about the character of these early Neolithic buildings."

Dr Ray said the fact more burial chambers and artefacts had been left at the site hundreds of years after it was first created showed its national importance.

"These subsequent finds show that 1,000 years after the hall burial mounds were made, the site is still important to later generations living 200 miles away - a vast distance in Neolithic terms," he said.

"For example, the axe and knife may not have been traded, but placed there as part of a ceremony or an ancestral pilgrimage from what is now East Yorkshire.

"So we witness an inter-connected community linking Herefordshire and East Yorkshire by marriage and by descent 5,000 years ago."