Israeli security sources have warned that if Hamas delays the release of the second group of hostages, Israel will resume ground operations in Gaza.
Earlier on Saturday, Hamas' military arm said that it decided to delay the release of the second group of hostages, until Israel "meets the terms of the agreement to allow humanitarian aid trucks into northern Gaza."
According to the security sources, on Friday as well "Hamas played during the last moments, and changed the route by which the hostages would be transferred, in opposition to what had been planned."
The sources added, "This morning we passed to northern Gaza no less than 61 trucks carrying humanitarian aid out of 200 which were brought in today, and in them were containers of gas and cooking oil."
A diplomatic source said: "All claims by Hamas that Israel supposedly violated the agreement - are untrue. This is an attempt at a publicity stunt by Hamas. Israel has fulfilled all of its commitments. Hamas is embarrassing the brokers - Egypt and Qatar."
Some of the families of the hostages who are expected to be released Saturday night have already arrived at Soroka Medical Center in Be'er Sheva, where they were expecting to meet their relatives - only to learn of the delay.
Later on Saturday night, an Israeli source said that, "There has been a breakthrough; we are optimistic."
"Hamas knows that if the hostages are not released by midnight, the IDF will resume ground operations in Gaza - and therefore it is trying to control the narrative."
MK Yuli Edelstein, who chairs the Knesset's Foreign Affairs and Defense Committee, responded to Hamas' claims, saying, "In Arabic there is a basic principle which translates to, 'Patience is key to victory.' They have patience, but so do we."
"They will try to pull the cord, but we will decide when it's time to tear the cord. They will try to play with us, and we will respond at the time and in the way that is right for us. With care, with determination. Every step precalculated, until they are all here. Until victory."