The EU's two top chiefs said Friday they were "shocked" and "deeply disturbed" by the deaths of more than 100 Palestinians after Israeli troops opened fire during an aid delivery, and demanded an investigation.

"Shocked and repulsed by yesterday's killing of innocent civilians in Gaza while desperately waiting for humanitarian aid," European Council President Charles Michel posted on X, formerly Twitter.

"An independent investigation should be launched immediately and those responsible held accountable," he said.

European Commission chief Ursula von der Leyen said she was "deeply disturbed by images from Gaza" and added that "every effort must be made to investigate what happened".

Hamas authorities in Gaza say 115 Palestinians were killed Thursday after Israeli troops opened fire during an aid delivery.

An Israeli source acknowledged the military opened fire on the crowd, adding that the soldiers believed the civilians "posed a threat".

Shortly after Michel and von der Leyen expressed their indignation, the European Commission announced it was strengthening aid funding for Palestinians.

Commission spokesman Eric Mamer said the EU "will proceed to paying 50 million euros ($54 million) to UNRWA and increase emergency support to the Palestinians by 68 million euros in 2024".

UNRWA is the UN agency for Palestinian refugees. Its funding from international partners came under threat after Israel accused some of its staff of participating in Hamas's October 7 attack on Israeli communities near Gaza.

UNRWA head Philippe Lazzarini said on Friday on X that the release of 50 million euros "comes at a critical time" and "will support the Agency's efforts to maintain lifesaving and essential services for Palestinian Refugees across the region."

The EU had said it was reviewing but not suspending its funding to UNRWA in light of the Israeli allegations.

Mamer told reporters UNRWA had agreed to a "series of conditions" including an EU-led audit, and that the next tranche of funds would be released "early next week," with a further 32 million euros to follow later.

The extra 68 million euros in humanitarian aid would go through various organisations like the Red Cross and the Red Crescent, Mamer said.