Workers came upon the site last year during the building of an Egyptian-funded housing development near Jabaliya.

Since then, crews have worked to excavate the 2,700sqm site with the support of French experts.

It has been described as the largest cemetery to be discovered in Gaza.

The coastal enclave, which is home to some 2.3 million people, boasts a rich history stemming from its location on ancient trade routes between Egypt and the eastern Mediterranean region.

However, a series of factors including Israeli occupation, 16-year rule by the Hamas militant group and rapid urban expansion have posed a threat to many of the besieged strip's archaeological treasures.

Against this backdrop, the unearthing of 60 graves at the site in January marked a major discovery, according to archaeologists.

That number has now grown to 135.

Rene Elter, a French archaeologist leading the dig, said researchers have studied more than 100 of the graves.

He said: "All of these tombs have almost already been excavated and have revealed a huge amount of information about the cultural material and also about the state of health of the population and the pathologies from which this population may have suffered."

Mr Elter pointed to the sarcophagi made of lead - one featuring ornate grape leaves, the other with images of dolphins - as exceptional finds.

"The discovery of lead sarcophagi here is a first for Gaza," he said.

Given the rarity of the lead tombs, Palestinian archaeologists suspect social elites were buried there.

Fadel al Otul said the cemetery probably used to be located in a city as the Romans used to place them near major settlements.

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Alongside the sarcophagi, Mr Elter's team is restoring unearthed skeletons and piecing together shards of clay jars.

The skeletons discovered at the site will be sent out of Gaza for additional analysis, according to Mr al Otul.

The remains are set to return to the Hamas-led Ministry of Antiquities and Tourism.

Mr Elter said the territory needs a dedicated team to oversee archaeological digs in Gaza.

"The Gazans deserve to tell their stories," he said.

"Gaza boasts a plethora of potential archaeological sites, but monitoring each one, given the rapid pace of development, is no small feat."