US President Joe Biden has sharply criticized Israel over the deaths of several members of an international non-profit organization. He said it has not done enough to protect aid workers and civilians in the Gaza Strip.

The World Central Kitchen said on Tuesday that seven of its members were killed in an Israeli airstrike. The group engages in the delivery of humanitarian food aid in the enclosure.

In a statement released on the same day, Biden said, "I am outraged and heartbroken." He called the humanitarian workers' deaths "a tragedy" and demanded that a swift investigation take place and its findings be made public.

The president also said, "This conflict has been one of the worst in recent memory in terms of how many aid workers have been killed."

Biden criticized Israel for not adequately protecting aid workers and civilians. He stressed that the United States will continue to press Israel to do more to get aid into Gaza and push hard for an immediate ceasefire.

Biden has repeatedly urged Israel to protect civilians, but with the series of deaths of humanitarian workers, his criticism has become stronger than before.