Relatives of Israeli hostages in Gaza said Tuesday that the decision to return to fighting could "sacrifice" their loved ones, after the military carried out a wave of air strikes in the Palestinian territory.

The Hostages and Missing Families Forum campaign group said it had received no response to its request to meet with Prime Minister Benjamin Netanyahu and other officials to hear how the remaining hostages would be "protected from the military pressure".

"Now it becomes clear — the public officials did not meet with them because they were planning the explosion of the ceasefire, which could sacrifice their family members," the group said.

Of the 251 hostages seized during the unprecedented October 2023 Hamas attack that sparked the war, 58 are still held in Gaza, including 34 the Israeli military says are dead.

The overnight air strikes were by far the deadliest since the January ceasefire, which had largely halted the fighting and saw the handover of 33 hostages, both living and dead, in exchange for Palestinian prisoners.

The health ministry in Hamas-controlled Gaza said at least 413 people were killed in the attacks on Tuesday.

Dozens of relatives of Israeli hostages in Gaza protested near Netanyahu's office and the parliament in Jerusalem on Tuesday.

"Hamas cannot be defeated" while there are captives in Gaza "unless the government consciously decided to give up the lives of our children", said Michel Illouz, father of Guy Illouz who was abducted and murdered on 7 October.

'What about the hostages?'

Several hostages released during the first phase of truce, which came into effect on January 19, posted messages of support for the captives on social media.

Freed British-Israeli hostage Emily Damari, who was released in January, wrote on Instagram that her "heart is broken", adding that she would continue to fight for the captives to return home.

Eliya Cohen, who returned to Israel on February 22, described the renewed strikes as a "death sentence".

The return of the hostages is a priority for many Israelis.

"This morning, the moment we realised that we were going back to war, the first thing I thought about was: what about the hostages? This is a death sentence for the hostages, and it's simply terrible," said Muriel Aranov, a 62-year-old pensioner living in Tel Aviv.

During a parliamentary committee meeting, far-right Finance Minister Bezalel Smotrich called for the removal of a relative of a hostage who had died in captivity, saying: "We've heard enough from you!"

Netanyahu on Tuesday took part in a security assessment with defence officials in Tel Aviv, including Defence Minister Israel Katz, his office said.

An earlier statement from Netanyahu's office said the strikes were ordered after "Hamas's repeated refusal to release our hostages, as well as its rejection of all of the proposals it has received from US presidential envoy Steve Witkoff and from the mediators".

"We are at an impasse, we have said 'yes' more than once to concrete proposals from the US special envoy to extend the ceasefire, and Hamas has said 'no'," foreign ministry spokesperson Oren Marmorstein said in a briefing.

"From now on, Israel will act against Hamas with increased military intensity," he added.