Cairo (AFP) – Egypt has denied that a controversial court ruling over Sinai's Saint Catherine monastery threatens the UNESCO world heritage landmark, after Greek and church authorities warned of the sacred site's status.

A court in Sinai ruled on Wednesday in a land dispute between the monastery and the South Sinai governorate that the monastery "is entitled to use" the land, which "the state owns as public property".

President Abdel Fattah al-Sisi's office defended the ruling Thursday, saying it "consolidates" the site's "unique and sacred religious status", after the head of the Greek Orthodox church in Greece denounced it.

Archbishop Ieronymos of Athens called the court ruling "scandalous" and an infringement by Egyptian judicial authoriities of religious freedoms.

He said the decision means "the oldest Orthodox Christian monument in the world, the Holy Monastery of Saint Catherine in Mount Sinai, now enters a period of severe trial -- one that evokes much darker times in history".

Sisi's office in a statement said it "reiterates its full commitment to preserving the unique and sacred religious status of Saint Catherine's monastery and preventing its violation".

The monastery was established in the sixth century at the biblical site of the burning bush in the southern mountains of the Sinai peninsula, and is the world's oldest continually inhabited Christian monastery.

The Saint Catherine area, which includes the eponymous town and a nature reserve, is undergoing mass development under a controversial government megaproject aimed at bringing in mass tourism.

Observers say the project has harmed the reserve's ecosystem and threatened both the monastery and the local community.

Archbishop Ieronymos warned that the monastery's property would now be "seized and confiscated", despite "recent pledges to the contrary by the Egyptian President to the Greek Prime Minister".

Greek Foreign Minister Giorgos Gerapetritis contacted his Egyptian counterpart Badr Abdelatty on Thursday, saying "there was no room for deviation from the agreements between the two parties", the ministry's spokesperson said.

In a statement to Egypt's state news agency, the foreign ministry in Cairo later said rumours of confiscation were "unfounded", and that the ruling "does not infringe at all" on the monastery's sites or its religious and spiritual significance.

Greek government spokesman Pavlos Marinakis said "Greece will express its official position ... when the official and complete content of the court decision is known and evaluated".

He confirmed both countries' commitment to "maintaining the Greek Orthodox religious character of the monastery".