Israel said on Wednesday it would keep blocking humanitarian aid entering Gaza, where a relentless military offensive has turned the Palestinian territory into a "mass grave", a medical charity said.Israel resumed air and ground attacks across the Gaza Strip on March 18, ending a two-month ceasefire with resistance group Hamas that had largely halted hostilities in the territory, with rescuers on Wednesday saying at least 11 were killed in strikes across Gaza.Israel had already halted the entry of aid into Gaza on March 2, exacerbating the severe humanitarian crisis in the war-battered territory.Israeli troops will remain in the buffer zones they have created in Gaza even after any settlement to end the war, Defence Minister Israel Katz said, as efforts to revive a ceasefire agreement faltered.Medical charity Doctors Without Borders (MSF) said Israeli military operations and the aid blockade had transformed Gaza into a graveyard for Palestinians and aid workers.The UN had warned on Monday that Gaza was facing its most severe humanitarian crisis since the war began in October 2023. At least 11 people were killed in air strikes, 10 of them in an attack on Gaza City, the civil defence agency said.Israel's campaign has killed 51,025 Gazans since the war erupted in October 2023, most of them civilians.Since resuming military operations last month, Israeli forces have carved out a broad "security zone" extending deep into Gaza and squeezing more than 2mn Palestinians into ever smaller areas in the south and along the coastline.