Egypt's foreign minister said on Monday the US should make clear to Israel what the consequences of a military push into the south Gaza city of Rafah on the border with Egypt would be, after Washington voiced opposition to such a move.

Prime Minister Benjamin Netanyahu reaffirmed to a cabinet meeting on Sunday that Israeli forces would thrust into Rafah, the last relatively safe place in the tiny, crowded Gaza enclave after more than five months of war, despite international pressure for Israel to avoid civilian casualties.

Israel's allies have heaped pressure on Netanyahu not to attack Rafah, where more than a million displaced people from other parts of the devastated enclave have sought shelter, without a plan to protect civilians.

"It is not enough for rhetoric, it is not enough to state opposition, it is also important to indicate what if that position is circumvented, what if that position is not respected," Egyptian Foreign Minister Sameh Shoukry said at a news briefing with United Nations Relief and Works Agency for Palestine Refugees chief Philippe Lazzarini in Cairo.

"It is also up to the international community and the United States, who have indicated their refusal to such an eventuality, to make clear what are the consequences if their appeals are not heeded," Shoukry added in English-language remarks.

He also warned that the humanitarian consequences and the loss of lives that would result from an Israeli ground assault on Rafah would be "catastrophic".

Egypt has warned before of the "dire consequences" of a potential Israeli military push near its border, where it controls the Rafah crossing - the focal point of efforts to deliver humanitarian aid into Gaza and allow out injured people and foreign passport holders.