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.

Aid groups’ inability to deliver aid has “left hospitals without basic supplies, children, people with disabilities, and older people dying from hunger and preventable illnesses”, the statement said.

Sean Carroll, CEO of American Near East Refugee Aid (Anera), said: “Anera has over $7 million worth of lifesaving supplies ready to enter Gaza – including 744 tons of rice, enough for six million meals, blocked in Ashdod just kilometers away”.

Israel said that any delays in delivering aid occur “only when organisations choose not to meet the basic security requirements intended to prevent Hamas’s involvement”.

Cogat, the Israeli military body in charge of aid, said nearly 20 organisations that completed the registration process are bringing aid into Gaza, with roughly 300 trucks entering daily.

The UN says 600 trucks of supplies a day are needed in Gaza.

The new guidelines introduced in March update the framework for how aid groups must register to maintain their status within Israel, along with provisions that outline how their applications can be denied or registration revoked.

Registration can be rejected if Israeli authorities deem that a group denies the democratic character of Israel or “promotes delegitimisation campaigns” against the country.

“Unfortunately, many aid organisations serve as a cover for hostile and sometimes violent activity,” Israel’s Diaspora Minister Amichai Chikli told the Agence France-Presse news agency.

“Organisations that have no connection to hostile or violent activity and no ties to the boycott movement will be granted permission to operate,” added Chikli.

Bushra Khalidi, Oxfam Policy Lead, said Israel had rejected more than $2.5m (£1.8m) of goods from entering Gaza.

She added: “This registration process signals to INGOs that their ability to operate may come at the cost of their independence and ability to speak out.”

The warning comes as Israel steps up its bombardment of Gaza City, in preparation for a plan to take control of the city.

Israel says it will provide humanitarian aid to civilian populations “outside the combat zones”, but has not specified whether that aid would be delivered by the Israel and US-backed Gaza Humanitarian Foundation (GHF).

Israel says the system is necessary to stop Hamas stealing aid, an accusation Hamas denies.

The UN this month reported that 859 Palestinians had been killed near GHF sites since May, a figure the GHF denies.

In the joint statement, Aitor Zabalgogeazkoa, MSF emergency coordinator in Gaza, said that the “militarised food distribution scheme has weaponised starvation”.

The secretary-general of MSF, Chris Lockyear, told the BBC that GHF was a “death trap”, and the humanitarian situation in Gaza was “hanging on by a thread”.

Hamas’s 2023 attack killed about 1,200 people in Israel, with 251 seized and taken into Gaza as hostages.

Israel’s offensive has since killed nearly 62,000 Palestinians, according to the Hamas-run health ministry. It says that 235 people including 106 children have also died due to starvation and malnutrition.