Egypt is mulling downgrading diplomatic relations with Israel, Egyptian officials have said, as the Israeli attack on Rafah in the southern Gaza Strip tests a longstanding peace agreement.
Israeli forces began their ground attack on Rafah last Tuesday by seizing the city's border crossing with Egypt, and then pushing east.
Over 1.4 million Gazans have been displaced to the city as a result of Israel's indiscriminate bombardment of the Gaza Strip, which has devastated the Palestinian enclave.
Egypt announced on Sunday its formal support for South Africa's case that accuses Israel of "genocidal acts" at the International Court of Justice (ICJ).
Issues started when Israel provided Cairo with advance warning just hours ahead of the assault on Rafah, US newspaper The Wall Street Journal cited Egyptian officials as saying.
"There is now a lack of trust," said Mohammed Anwar Sadat, a former Egyptian MP who shares a name with his uncle, the late Egyptian president who signed a 1979 peace agreement with Israel.
"And there is now a kind of suspicion from both sides actually."
Sadat said the present disagreement was the worst crisis in the Israel-Egypt relationship since the 1979 peace treaty.
The advance Israeli warning to Egyptian intelligence on Monday last week came after months of talks between officials on both sides regarding the assault on Rafah.
Israel said the important crossing with Egypt would not be impacted and people would be allowed weeks to evacuate.
An Egyptian official said "none of these assurances materialised" and that Israel provided Cairo "a very short notice about entering the crossing".
The Rafah crossing with Egypt is located along the Salah Al-Din (Philadelphi) corridor, a buffer zone controlled by Egypt.
Alongside the Karm Abu Salem (Kerem Shalom) crossing with Israel, Rafah is a key lifeline for humanitarian aid to enter the Gaza Strip, which is now facing catastrophic levels of hunger according to the UN.
Egypt is also an important party in talks - alongside Qatar and the US - on trying to broker a ceasefire between Israel and Hamas.
However, Egypt has reportedly declined to work with Israel to operate the Rafah crossing since the latter seized it.
One Egyptian official said there were currently "no plans to suspend ties or throw away" the Camp David Accords signed the year before the 1979 agreement.
"But as long as Israeli forces remain at [the] Rafah crossing, Egypt will not send a single truck to Rafah," the official said.
The Israeli capture of Gaza's Rafah crossing has angered Cairo as it takes away a tool it can use to pressure Hamas, according to observers.
"There is no deal, and Israel is endangering [aid flows], it puts them in a really hard position," an Israeli official said.
"The fact that aid hasn't come in, it's bad for them, but it's very bad for us."
Israel is under obligation to the ICJ, the UN's top court, to bring relief into the Palestinian enclave, the official highlighted.
Israel's war on Gaza has so far killed at least 35,173 people, according to the territory's health ministry.
Ambulances, hospitals, and residential buildings have been attacked as Israeli forces carry out their brutal military offensive.
Almost 450,000 people have been forcibly displaced from Rafah since last Monday, the United Nations Palestinian refugee agency UNRWA has estimated.
