Questions are being asked about whether Israel's strike on a refugee camp to kill a senior Hamas leader is a war crime.
Under international humanitarian law, civilians cannot be targeted, attacks cannot be indiscriminate and innocent casualties cannot be excessive.
United Nations special rapporteur on counter-terrorism and human rights Ben Saul said more information was needed about strikes on the Jabaliya refugee camp in Gaza.
Gaza's health ministry said at least 50 people were killed in the first strike on the refugee camp, which Israel said also killed Hamas militants and a senior leader.
Professor Saul, who is also an international law expert at the University of Sydney, said Israel had an obligation to minimise casualties.
Israel should have known from past attacks that striking an area with complex tunnel systems would lead to a collapse of surrounding buildings and kill innocents within them despite it being "a weighty military objective".
"Should they have sought more information to figure out whether civilians were present and how many? Did they choose the right kinds of weapons and attack at the right time of day, et cetera, to minimise civilian casualties?" Prof Saul told ABC radio.
"All of that goes to the knowledge and intention of the Israeli targeters and that's an important part of whether any war crime has been committed."
Israel has defended its actions, saying they are in accordance with international law given it has a right to self defence and to strike military targets hiding amongst civilian infrastructure.
The fact civilians were warned to evacuate the area before the strikes also showed compliance with international law, Israeli forces argued.
But regardless of whether civilians left, "Israel always still has an obligation to ensure that it does not cause excessive civilian casualties or mount indiscriminate attacks", Prof Saul said.
Israel's blockage of humanitarian aid and supplies into Gaza was the most clear-cut case for war crimes, he said.
"This is one of the clearest violations of international humanitarian law by Israel in this conflict ... starvation is a war crime.
"There's a real case to answer for the Israeli military and political leadership which ordered that complete siege."
Prof Saul said no serious arguments could be mounted to defend Hamas, designated a terrorist organisation by Australia, following the October 7 attack that killed at least 1400 Israelis and led to more than 200 hostages being taken.
"Their murders, their hostage-taking, the indiscriminate rocket fire, all of those are such clear violations," Prof Saul said.
"Israel does have a serious targeting process, which takes into account the advice of lawyers and so on.
"(But) Israel has a pretty poor record of investigating its own forces and an even poorer record of holding them to account where there have been independently verified and documented cases of violations of the law."
