More than 100 organisations have signed a joint letter calling on Israel to stop the "weaponisation of aid" into Gaza, as "starvation deepens".
Humanitarian groups, including Oxfam and Médecins Sans Frontières (MSF), say they are increasingly being told they are "not authorised" to deliver aid, unless they comply with the stricter Israeli regulations.
Groups risk being banned if they "delegitimise" the state of Israel or do not provide detailed information about Palestinian staff, the letter says.
Israel denies there are restrictions on aid and says the rules, introduced in March, ensure that aid "reaches the population directly and not Hamas".
According to the joint letter, most major international non-governmental organisations (NGO) have been unable to deliver a single truck of lifesaving supplies since 2 March.
They say Israeli authorities "have rejected requests from dozens of non-governmental organisations to bring in lifesaving goods", citing the new rules. More than 60 requests were denied in July alone.