"It is strictly forbidden to deal with, work for, or provide any form of assistance or cover to the American organization (GHF) or its local or foreign agents," an interior ministry statement said.

"Legal action will be taken against anyone proven to be involved in cooperation with this organization, including the imposition of the maximum penalties stipulated in the applicable national laws," it added, without giving further details.

The GHF said in a statement in response that it had delivered million of meals "safely and without interference."

"This statement from the Hamas-controlled Interior Ministry confirms what we ve known all along: Hamas is losing control," the GHF said.

The GHF began distributing food packages in Gaza at the end of May, overseeing a new model of deliveries which the United Nations says is neither impartial nor neutral, Reuters reported.

Since Israel lifted an 11-week aid blockade on Gaza on May 19, the United Nations says more than 400 Palestinians have been killed while seeking handouts of aid.

A senior U.N. official said on Sunday that the majority of people killed were trying to reach aid distribution sites of the Gaza Humanitarian Foundation.

Israel s military acknowledged on Monday that Palestinian civilians had been harmed near the distribution centres and that its forces had been issued with new instructions following what it called "lessons learned."

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Israel has said its forces operate near the centres in order to prevent the aid from falling into the hands of militants, which Hamas denies.

More than 170 international humanitarian groups signed a letter this week calling on governments to press Israel to end use of the GHF to deliver aid and return to letting in aid mainly through U.N.-run channels.

The GHF has said it has delivered more than 52 million meals to hungry Palestinians in five weeks, while other humanitarian groups had "nearly all of their aid looted."