Human Rights Watch said on Thursday that Israel's total blockade of the Gaza Strip, in place since 2 March, has become "a tool of extermination".
"Israel's blockade has transcended military tactics to become a tool of extermination," HRW interim executive director Federico Borello said in a statement.
Israel blocked all aid from entering Gaza on 2 March, before resuming its military operations on 18 March after talks to prolong a six-week ceasefire collapsed.
Israel said the pressure is aimed at forcing Hamas to free captives in Gaza.
Israel denies that a humanitarian crisis is unfolding in Gaza.
In its statement, HRW said that "the Israeli government's plan to demolish what remains of Gaza's civilian infrastructure and concentrate the Palestinian population into a tiny area would amount to an abhorrent escalation of its ongoing crimes against humanity, ethnic cleansing, and acts of genocide".
For weeks, humanitarian organisations and the United Nations have warned that supplies from food and clean water to fuel and medicine are reaching new lows.
Borello also criticised "plans to squeeze Gaza's 2 million people into an even tinier area while making the rest of the land uninhabitable".
The UN estimates that 70 percent of Gaza is now either an Israeli-declared no-go zone or under evacuation order.