Israel has issued a fresh warning to civilians in northern Gaza, saying its military is about to carry out intensive operations there.
It comes after Israel said rockets were fired from the area.
Palestinians across the war-ravaged Gaza Strip have marked the start of one of Islam's most important holidays, amid little hope the conflict will end any time soon.
Much of Gaza lies in ruins, with men and children forced to hold the traditional Eid al Adha prayers in the open air, and as food supplies dwindle.
Food and aid were blocked from entering the Palestinian territory for more than two months, but a trickle of supplies has been allowed in over the last few weeks.
The UN said it cannot distribute much of the aid, due to the risk of looters and restrictions on movement.
"This is the worst feast that the Palestinian people have experienced because of the unjust war against the Palestinian people," said Kamel Emran after attending prayers in the southern city of Khan Younis.
"There is no food, no flour, no shelter, no mosques, no homes, no mattresses... The conditions are very, very harsh."
The Islamic holiday begins on the 10th day of the Islamic lunar month of Dhul-Hijja, during the Hajj season in Saudi Arabia.
It is the second year Muslims in Gaza have been unable to travel to the country to perform the traditional pilgrimage.
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The war broke out after the 7 October 2023 attack on Israel by Hamas-led militants. Some 1,200 people were killed and around 250 others were abducted and taken to Gaza.
Hamas is still holding 56 hostages, with a third of them believed to be alive. The rest have been released in ceasefire agreements, with forces rescuing eight living hostages from Gaza and recovering dozens of bodies.
Israel has killed more than 54,000 Palestinians, mostly women and children, in its military campaign, according to the Gaza health ministry, which does not distinguish between civilians or combatants in its figures.
Around 90% of the population of two million has been displaced.
(c) Sky News 2025: Gaza marks start of Eid with outdoor prayers in rubble - as Israel warns of intens