There is no guarantee the "very significant" will ever be fully excavated.

The Minister for Culture, Heritage and the Gaeltacht has welcomed a fascinating new archaeological discovery near Newgrange.

The recent heatwave has been credited with exposing the discovery of a possible henge – or circular enclosure – near the famous County Meath monument.

After extreme dry weather, features hidden under the surface are exposed as the grass above them remains slightly greener than elsewhere.

Aerial photographs taken by historian and author Anthony Murphy uncovered the “very substantial and previously unrecorded features.

Mr Murphy said he is "still coming back down to Earth" after making the discovery.

“I had a gut feeling, when we first saw what was in the field, that it was something very, very special and very unique," he said.

“But then yesterday when we got into conversation with some of the archaeologists, I think it was only then we realised how spectacularly big the find was - and how excited the archaeological community is about it."

Mr Murphy came upon the find with fellow local photographer Ken Williams.

He is in the process of reporting it to the National Monument Service, however there is no guarantee it will ever be excavated.

"The monument is on private farmland," he said. "A lot of people are asking if there is going to be an excavation."

"The simple answer is that is highly unlikely.

"There are a lot of monuments in the UNESCO World Heritage Site at Newgrange - probably around 200 monuments in that area and the great majority of them have never been excavated."

He said that over the last ten years a number of monuments have been discovered and, while they are protected national monuments, "ultimately, a dig has to be funded and it has to be done with the agreement of landowners." 

The feature could measure up to 200 metres in diameter and is believed to have been built around 2,500 BC – 500 years after Newgrange.

"We are looking at huge amount of manual labour and time and dedication to the task by a community in the late Neolithic and early Bronze Age that likely were not using metal tools or anything like the kind of modern plant equipment that we would use in contraction projects," said Mr Murphy.

"Sheer will and manpower put these things together." 

The Department of Culture, Heritage and the Gaeltacht has described the find as “very significant.”

Its National Monuments Service has been informed and is now investigating the find further.