DOHA/GAZA, Jan 14 (Reuters) - Israeli tanks and aircraft hit targets in southern and central Gaza on Sunday and there were fierce gun battles in some areas as the war reached 100 days since the Oct. 7 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.

Fighting was 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 military said several militants were killed.

The military also said its forces destroyed several rocket pits used by Hamas to fire missiles at Israel.

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.

Speaking through video link to a conference in Istanbul, Hamas leader Ismail Haniyeh praised the Oct. 7 attack by the group's fighters who rampaged through Israeli communities around the Gaza Strip, 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 years-long Israeli blockade of the Gaza Strip, which Hamas has controlled since 2007.

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 the northern Gaza Strip, 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 Dec. 16, in response to the death of a journalist in Gaza, the Israeli army said "the IDF 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. The military says, though, the next phase of the war will see more targeted operations against the movement's leaders and military 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 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 the community of Kfar Yuval, killing one person and causing a number of other casualties.

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 two separate incidents in Hebron and Jericho in the West Bank.

The Israeli military said two Palestinians in a car rammed through one of its checkpoints near Hebron and opened fire on pursuing troops. They were killed by return fire, the military statement said. There was no immediate comment on the 14-year-old boy's death in Jericho.

In Rafah in the southern Gaza Strip, Nana, a 17-year-old high school student displaced from northern Gaza, said 100 days of war "turned our life upside down."

"We demand the occupation not only to end the war but also compensation for the psychological damage of displacement and the hardships endured," she said. (Reporting and writing by Nidal al-Mughrabi in Doha, Fadi Shana in Gaza; Additional reporting by Ari Rabinovitch in Jerusalem, Ali Sawafta in Ramallah; Editing by Tomasz Janowski and Hugh Lawson)