Israeli tanks and aircraft have hit targets in southern and central Gaza while fierce gun battles have taken place in some areas, as the war reached 100 days since the 7 October attack led by gunmen from the Islamist Hamas movement.
Communications and internet services were down for the third day running, complicating the work of emergency and ambulance crews trying to help people in areas hit by fighting.
The clashes were concentrated in the southern city of Khan Younis, where Hamas said its fighters hit an Israeli tank, as well as in Al-Bureij and Al Maghazi in central Gaza, where the Israeli military said several fighters were killed.
The military also said it destroyed several silos used by Hamas to fire missiles at Israel.
Hamas showed it retained rocketry capacity, launching a fresh salvo at Ashdod, an Israeli town 40km away. There was no word of any casualties.
A spokesman for the group's armed wing has said many of the hostages held by Hamas in Gaza are likely to have been killed, and blamed the Israeli leadership for their fate.
"The fate of many of the enemy's hostages and detainees has become unknown in recent weeks and the rest have all entered the tunnel of the unknown due to the Zionist aggression," Abu Obeida said in a televised statement.
"Most likely, many of them were killed recently, the rest are in great danger every hour and the enemy's leadership and army bear full responsibility."
Abu Obeida said the group's allies from the "axis of resistance" had informed Hamas they would "expand their attacks" against Israeli troops in the coming days.
"After 100 days of battle... this is the enemy's leadership, gulping down pain and wading through the mud of failure and setback," he said.
Over the past 24 hours, the Gaza health ministry said 125 people had been killed and 265 wounded, bringing the total number confirmed to have been killed since the start of the war to almost 24,000, with more than 60,000 wounded.
Israel's military said it has killed around 9,000 Palestinian fighters, and lost 189 soldiers so far
Speaking through video link to a conference in Istanbul, Hamas leader Ismail Haniyeh praised the 7 October attack by the group's fighters who rampaged through Israeli communities around Gaza, killing more than 1,200 people and seizing around 240 hostages, according to Israeli tallies.
"We are not seekers of wars. We are seekers of freedom," he said, saying the attack was, in part, a response to the blockade Israel and neighbouring Egypt placed on Gaza after Hamas seized control of the territory in 2007.
Read more:
100 days on, what's the state of play in Israel-Hamas war?
The Iranian-backed group is sworn to Israel's destruction.
The Israeli military says it has shifted to a new phase of the war, focused on the southern end of the territory, where almost 2 million people are now sheltering in tents and other temporary accommodation, after the initial phase centred on clearing the northern end including Gaza City.
In northern Gaza, health officials said an Israeli air strike killed a local journalist, raising the number of journalists killed in the Israeli offensive to more than 100, according to the Gaza government media office.
In a statement on 16 December, in response to the death of a journalist in Gaza, the Israeli army said it "has never, and will never, deliberately target journalists".
Prime Minister Benjamin Netanyahu has brushed off calls for a ceasefire, saying Israel will keep going until it achieves complete victory over Hamas and recovers 132 remaining hostages.
The military says, though, the next phase of the war will see months of more targeted operations against the movement's leaders and positions.
On Israel's northern border with Lebanon, where there has been a constant, low-level exchange of fire between troops and fighters from the Iran-backed Hezbollah militia, the Israeli military said it killed four armed militants trying to cross the border.
It said several anti-tank missiles were fired into northern Israel, one of which hit a house in Kfar Yuval village. Medical officials said a 76-year-old woman and her son were killed. The son was in the village's security squad, the military said.
The war in Gaza has also stoked violence in the Israeli-occupied West Bank. The Palestinian health officials said Israeli forces killed three Palestinians, including a 14-year-old boy, in incidents in Hebron and Jericho in the West Bank.
Asked about the boy killed in Jericho, the military said soldiers had shot at Palestinians who threw explosives devices at them.
