Flares dropped by Israeli forces above the Palestinian enclave. AFP

The war in Gaza ground into the new year on Monday, with Hamas firing a barrage of rockets at Israel just as the clock struck midnight and two dozen people killed overnight in Israeli strikes on the Palestinian territory.

Air alert sirens sounded across Israel as 2024 began, and AFP journalists in Tel Aviv witnessed missile defence systems intercepting rockets overhead, with some revellers in the streets below rushing for cover while others kept up the party with a shrug.

"We were all afraid on the corners... my heart was pounding," Gabriel Zemelman, 26, said in front of a bar after the rocket fire.

"It's terrifying. You just saw the life we live, it's crazy."

The Ezzedine Al Qassam Brigades, the armed wing of Hamas, claimed responsibility for the attack in a video published on social media, saying they had fired M90 rockets in "response to the massacres of civilians" carried out by Israel.

The Israeli army confirmed the attack, without initially reporting any casualties or damage.

Surrounded by partiers, server Ran Stahl, 24, said he didn't have the heart to celebrate, not since one of his friends was killed in Hamas's attack on the Supernova music festival.

"The minute I start to dance, I feel guilty — the sadness and mourning come back," he said.

In Gaza, overnight Israeli strikes killed at least 24 people, according to the Hamas-run health ministry, with attacks reported across the length of the territory.

Israel vowed to destroy Hamas in response, launching a punishing offensive in the Gaza Strip that has reduced vast areas to a ruined wasteland and killed at least 21,822 people, mostly women and children, according to the territory's health ministry.

The Israeli army says 172 of its soldiers have been killed inside Gaza, with the war showing no signs of stopping.

Prime Minister Benjamin Netanyahu warned on Saturday that the fighting would last "many months until Hamas is eliminated and the hostages are returned".

Agence France-Presse