Archaeologists have uncovered a rare example of a grave that has been kept almost intact for 4000 years.

The burial chamber, which was found in Forteviot, Perthshire, is thought to have been used as the final resting place of a "significant" person, who may have been a community leader or religious figure in the Early Bronze Age.

His grave lay hidden by a four-ton sandstone slab until a crane was used to lift the massive stone, revealing artefacts including a bronze dagger, a leather bag, wooden bowl and portions of the original birch bark coffin.

The grave was found at Forteviot, where Kenneth MacAlpin, the first king of a united Scotland, died in AD858, and Historic Scotland said it was a "rare and exciting" discovery.

Dr Noel Fojut, head of Historic Scotland archaeology programmes and grants, said: "Bronze Age cist burials are not uncommon finds in Scotland, with a handful turning up most years, usually in building or agricultural operations.

"But early indications from this new discovery, both the quality of the grave goods and also the careful construction and decoration of the burial cist, suggest that the individual buried here was someone of the highest social standing - and that is very rare and very exciting.

"The fact that this important individual was buried at a location which we know was one of the main power centres in the country almost 3000 years later is remarkable, but it is far too early to decide if this is coincidence or continuity.

"For archaeologists, there is excitement not just about the social status of the burial but also about the preservation of the contents of the grave: the wooden inner coffin and other organic material will have the potential to tell us a great deal about the environment in which this individual lived and died.

"Such material usually decays before discovery, and when it survives it is very fragile and is often lost when cists are discovered by accident, so it is a huge bonus that this grave was located and excavated under controlled archaeological conditions.

"Much further study will be needed, as well as conservation work on the grave's contents, but this clearly has the potential to be one of Scotland's prehistoric finds of the decade."

The sandstone slab was first discovered by archaeologists from Glasgow and Aberdeen Universities working on the Strathearn Environs & Royal Forteviot (SERF) project last summer, but the team had to wait until this year to investigate further.

A giant crane was brought in to lift the stone, which had sealed the grave so well that several materials buried alongside the person survived intact. The only remains of the person left consisted of "grave wax", the residue left after a body decays.

The archaeologists said the dagger buried in the grave suggested it was a man and carvings which decorated the underside of the stone indicate that he was a significant person.

Dr Kenneth Brophy, SERF co-director, said: "Whoever he was, he was obviously extremely important to the community.

"Usually graves would be covered with slabs the same size as the grave. This stone is out of proportion. It would have been dragged here using ropes and it suggests that whoever was buried here deserved a huge amount of effort."

The artefacts will be examined by the AOC Archaeology Group in Edinburgh.

Professor Stephen Driscoll, SERF co-director, said: "This excavation is part of a long-term project to study the link between the emerging kingdom of medieval Scotland and its ancient prehistoric remains.

"This burial provides the strongest evidence of the presence of ancestral graves which may have been regarded as mythological heroes by the Picts who were also buried nearby in Forteviot."