The return to hostilities in Gaza must cease and humanitarian aid and commercial essentials be allowed to enter the embattled territory, the emergency relief co-ordinator for the United Nations said yesterday.UN Under-Secretary-General Tom Fletcher spoke at a UN Security Council briefing after Palestinian health authorities said Israeli airstrikes pounded Gaza, killing more than 400 people, threatening the complete collapse of a two-month ceasefire as Israel vowed to use more force to free hostages held by Hamas.“Overnight our worst fears materialised,” he said. “Airstrikes resumed across the entire Gaza Strip. Unconfirmed reports of hundreds of people killed ... once again, the people of Gaza are living in abject fear.”“Humanitarian workers remain on the ground ... ready to provide life-saving support to survivors and to carry out humanitarian operations,” Fletcher added. “We must be allowed to do so.”The UN official said that since March 2, Israeli authorities had cut off the entry of all lifesaving supplies – food, medicines, fuel, cooking gas – for 2.1mn people in Gaza and UN requests to collect aid sitting at Kerem Shalom crossing had been rejected.“This total blockade of life saving aid, basic commodities and commercial goods will have a disastrous impact on the people in Gaza who remain dependent on a steady flow of assistance into the strip,” he said.He said that the ceasefire had showed what was possible and enabled aid delivery.“We cannot and must not accept a return to pre-ceasefire conditions or the complete denial of the entry of humanitarian relief,” Fletcher said “Civilians must be protected, and their essential needs must be met. International law must be respected.”