Hamas ominously released what it called a "parting image" Saturday of the remaining 48 Israelis being held captive in Gaza, as the Jewish state's ground troops prepare to close in on Gaza City.

The image is a compilation of the faces of the captives, with the name Ron Arad inscribed below each one.

Arad was an Israeli air force pilot who went missing during a 1986 bombing mission in southern Lebanon, who is believed to have been captured and since died. He is still officially classified as missing.

The terror group blames Israeli Prime Minister Benjamin Netanyahu for rejecting a last-minute cease-fire and hostage deal, and Israeli Defense Forces Chief of Staff Eyal Zamir for agreeing to carry out the prime minister's military takeover of Gaza City -- despite his own opposition.

"Because of Netanyahu's refusal, and Zamir's capitulation, a parting image as the military operation in Gaza City begins," reads the text above the twisted propaganda image.

Gaza City, the largest city in the Palestinian enclave, is considered Hamas' last remaining stronghold.

The Israeli Air Force continued to press its military offensive overnight, striking 100 targets in the Strip, including tunnels, buildings and other infrastructure it said was being used by Hamas.

The IDF warned Friday it would use "unprecedented force" in Gaza City and estimates it has destroyed up to 20 Gaza City tower blocks -- suspected Hamas hideouts -- over the past two weeks.

Palestinian residents were urged again Saturday to flee the area.

The military estimated 480,000 Gaza City residents have fled since late August.

Around 1 million Palestinians were believed to be residing in the city before the IDF launched its major offensive.

The IDF reported that several Hamas operatives, including field commanders, were killed in the devastating strikes overnight.

The terror group, in anticipation of IDF forces encircling the critical city, issued its strongest warning yet Thursday, saying the military takeover of Gaza City meant Israel had lost any chance of having the hostages returned -- dead or alive.

A Hamas political official who survived Israel's strike on Doha earlier this month echoed those comments, in his first appearance since being targeted in the failed bombing in Qatar.

"The operation in Gaza City will be met with fierce resistance, and the death and destruction that the enemy tries to bring to Gaza's streets will befall its soldiers," said Hamas senior official Bassem Naim on Qatari television Thursday, according to the Times of Israel.

"Those who harm us during the operation in Gaza City will also harm the hostages, living and dead."

Meanwhile, large nationwide rallies were held in Israel on Saturday evening to protest against the ground operation, which was launched this week.

Families of hostages accused Netanyahu of letting their loved ones die for political gain, by continuing to fight instead of negotiating an end to the war.

"The blood of our loved ones is, for him, nothing more than a political tool to cling to power," they said in a statement read outside Netanyahu's residence in Jersusalem. "As long as there is war, Netanyahu has a government."

Hamas releases 'parting image' of 48 remaining captives, vowing that...