Rabbi Simcha HaCohen Kook, Rabbi of Rehovot and member of the Chief Rabbinate of Israel, warned that the government relinquishing David's Tomb to the Vatican would be a "national disgrace."
"Twenty years ago they wanted to do something similar, to give the burial place of King David away - and again today," the Rabbi stated to Arutz Sheva Wednesday.
"Imagine if another nation did something similar [by giving away an ancient heritage or religious site - ed.] - there would be an outcry," he continued. "Now when Jews do it, the world is silent. We are tumbling down a deep abyss."
Rabbi Kook noted that, unlike some Jewish religious sites, all the Rabbis in Israel have declared that King David's Tomb really is on Mount Zion - making giving the site away a national tragedy.
"The Ben Ish Chai wrote a special song for it, the Holy Ari confirmed the gravesite's location in Israel, Rabbi Moshe Hagis also did," he said. "The Maharil Diskin and Rabbi Shmuel Salant, Rabbis of Jerusalem, wrote that those who doubt Mount Zion is the burial place of King David, is uncouth and ignorant. Tomorrow they will come and say that Rabbi Shimon Bar Yochai is not buried in Meron - how did we get here?"
The Rabbi also expressed confusion over the status of the deal, rumors of which have floated around Israeli media for months - but have yet to be confirmed in Italian media.
"For months, the Vatican said that everything is agreed, and that King David's Tomb is signed away," he lamented. "What can we do? If they give Catholics the room above the Tomb of David, we cannot pray there."
Rabbi Kook added that the issue has incredible religious implications.
"This is as if the Jews are admitting to the Christians that they, not us, are the 'true descendants' of King David," he warned. "Young Jews will want to come here to pray and instead see masses of Christian worshippers."
"Who knows if this could cause a wave of conversions [to Catholicism]?" he continued. "What will happen in the World to Come when we have to testify [before G-d] and say that we lived in a generation which handed over King David's Tomb? A government who does such a thing is forbidden to belong to the people of Israel, this is an anti-Israeli government."
Concerns over a possible transfer of the property have been raised multiple times over the past several months. Earlier this month, an Israeli diplomatic source told Arutz Sheva that the Israeli government has no intention of transferring control over the site to the Church.
However, Rabbi Yaakov Sevilia, an activist for King David's Tomb, told Arutz Sheva that there is a deal in the works - which would see David's Tomb given to Christians, and the Temple Mount to Muslims. He cited journalist Gulio Meotti, who contributes regularly to Arutz Sheva, as the source for this knowledge.
MK Tzipi Hotovely (Likud) has also written a stern letter to Prime Minister Binyamin Netanyahu over the issue, noting its political significance in terms of Israel's history and heritage.
"It is inconceivable that this place will be transferred to foreign hands, such the Torahs and the Star of David will be swallowed in a sea of crosses," the Deputy Minister wrote.
''Transferring the rights to the gravesite of David to Christian hands would be similar to Moshe Dayan's decision to entrust the keys to the Temple Mount to the Jordanian Waqf."
Hotovely warned that David's Tomb, like the Temple Mount, could become restricted to Jewish access and prayer - and has serious political and religious implications.
"David's Tomb is also evidence of Jewish sovereignty in ancient Israel," she declared. "Handing over the grave of the great leaders of the ancient Jewish state, is in fact an agreement with the Palestinians - who rewrite history and challenge the legitimacy of the State of Israel."