The latest round of ceasefire negotiations in the ongoing war in the Gaza Strip, held in the Egyptian capital Cairo, has reached a dead end again, amid a "difficult stalemate" in the talks, according to diplomatic sources.

The 13-member Israeli delegation, which arrived in Cairo earlier on Sunday, left, according to sources at Cairo airport, the German Press Agency. Representatives of the Palestinian Hamas movement, who came from Doha to see the progress of the indirect talks, also left.

A senior Hamas official said Israel must abide by the promises it made in early July and the peace plan proposed by US President Joe Biden.

The official said, according to the German News Agency, that Hamas is ready to implement the previously agreed-upon arrangements, and that any agreements regarding the war must include a permanent ceasefire and a complete withdrawal of Israeli forces from Gaza.

In addition, White House National Security Advisor Jake Sullivan confirmed on Sunday that the United States is still making efforts in Cairo to reach a ceasefire agreement in Gaza.

He added that the United States is concerned about the escalation of the conflict in the Middle East into a wider war, according to Reuters news agency.

Sullivan also said, in a press conference, that the administration of President Joe Biden is in constant contact with Israel regarding the current situation with the Lebanese Hezbollah group.

Two Egyptian security sources told Reuters earlier on Sunday that talks on Gaza in Cairo ended without reaching an agreement, as neither Hamas nor Israel agreed to a number of solutions presented by mediators, raising doubts about the chances of progress in the latest efforts to end the 10-month-old war.

Months of talks have failed to reach an agreement to end Israel's devastating military campaign in Gaza, or to release the remaining hostages held by Hamas during its Oct. 7 attack on Israel that sparked the war.

The main points of contention in the ongoing talks, mediated by the United States, Egypt and Qatar, include the Israeli presence in the so-called Philadelphi Corridor, a narrow strip of land 14 kilometers long along the southern border of the Gaza Strip with Egypt.

An Egyptian source said that the mediators proposed a number of alternatives to the presence of Israeli forces on the Philadelphi Corridor and the Netzarim Corridor, which passes through the middle of the Gaza Strip, but the two parties did not accept any of these alternatives.

The source added that Israel also expressed reservations about the number of detainees that Hamas is demanding to be released, as Israel demanded that they leave Gaza if they are released.

Hamas said Israel had backed away from its commitment to withdraw its forces from the Philadelphi corridor and set new conditions, including screening displaced Palestinians as they return to the more densely populated northern Gaza Strip when the ceasefire begins.