The United Nations denounced a new Israeli-backed aid operation in southern Gaza on Wednesday, a day after the chaotic launch of the initiative, when thousands of hungry Palestinians stormed a food distribution site, prompting Israeli forces to fire warning shots.

The episode further raised questions over Israel’s latest attempt to overhaul the provision of aid to Gazans, in what Israeli leaders call an attempt to sideline Hamas. The U.N. and many other humanitarian groups have boycotted the initiative, which has also drawn anger from many of Israel’s Western backers.

The Israeli initiative comes amid rising international condemnation over Israel’s threats to launch a new ground offensive against Hamas, on the heels of a two-month blockade on humanitarian aid that ended last week. Benjamin Netanyahu, the Israeli prime minister, has promised the planned military campaign will be a decisive blow against Hamas.

On Wednesday, as the Israeli initiative, known as the Gaza Humanitarian Foundation, said it had set up two distribution hubs and provided thousands of aid parcels without incident, Europe diplomats further criticized the program.

“The disproportionate use of force and the deaths of civilians cannot be tolerated,” said Kaja Kallas, the European Union’s top diplomat, adding that aid “must never be politicized or militarized.”

Under the new Israeli-designed system, four aid sites in southern Gaza are being secured by Israeli soldiers and overseen by private U.S. contractors. Previously, the United Nations led the distribution of aid in the enclave, but Israeli officials have been eager to bypass the world body, accusing it of anti-Israel bias and of failing to prevent Hamas from hoarding supplies.