An archaeological discovery described as the most important in 18 years has been made at the site of the Tarxien temples.

Malta Environment Planning Authority (Mepa) officials discovered megaliths and other remains, which are most probably prehistoric, during development works within the buffer zone of the Neolithic temples.

The site was described by archaeologist Kevin Borda as the most important one since a burial ground was unearthed at the Brockdorff Circle in Xagħra in 1990. It lies within a plot of land measuring 25 by eight metres towards the back of the plot.

The megaliths and boulders were found together with pottery shards made up of rims, handles and bases in an area measuring roughly four by four metres. The shards have scratched and incised motifs which date them to the Temple Period.

The discovery was made during a routine inspection by the Heritage Planning Unit within the Forward Planning Division at Mepa, following the issue of a permit for the re-development of an existing building within the buffer zone. The zone was scheduled by Mepa in 1998.

During the inspection it was noted that demolition and site clearance works had uncovered a number of features which date back to 4,100-2,500 B.C.

"The importance of the site is enhanced by the possibility that there are other structures beneath the intensive building works that were carried out in the 1980s in the Tarxien area," Mr Borda said.

In line with the Cultural Heritage Act, 2002, Mepa has submitted the information to the Superintendence of Cultural Heritage which has confirmed the interpretation of the features as identified by the Heritage Planning Unit. The agencies are now collaborating to investigate the features and ensure their preservation.