Speaking at a political fundraiser in Boston, Biden said accounts of "unimaginable cruelty" had been shared over the past few weeks.
"Reports of women raped — repeatedly raped — and their bodies being mutilated while still alive, of women's corpses being desecrated, Hamas terrorists inflicting as much pain and suffering on women and girls as possible and then murdering them. It is appalling," Biden said.
The president called on international organizations, civil society and individuals to condemn sexual violence "without exception."
Israeli police are investigating possible sexual crimes by some of the few hundred people that they arrested after the October 7 attack. Israel's justice ministry has said "victims were tortured, physically abused, raped, burned alive, and dismembered."
In a statement on its Telegram channel, Hamas said it denounced Biden's "attempt to falsely accuse" its fighters of committing sexual violence and rape on October 7.
The Islamist group said Biden was joining Israel's effort to cover up war crimes in Gaza committed with U.S. support and to mislead public opinion.
Israel held an event at the United Nations in New York on Monday focused on sexual violence against women during the Oct. 7 attack. Israel has been critical of the world body's response to the attacks.
"As a global community we must respond to weaponized sexual violence, wherever it happens, with absolute condemnation. There can be no justification and no excuses. Rape as a weapon of war is a crime against humanity," former U.S. Secretary of State Hillary Clinton told the event in a pre-recorded video.
On Tuesday, Biden blamed Hamas for the collapse of a truce last week that had halted Israel's retaliatory military campaign against Gaza, saying the militant group's "refusal to release the remaining young women is what broke this deal."
Israel and Hamas have accused each other of wrecking negotiations to extend the week-long pause in fighting, which resumed on December 1.
Since then, Israeli forces have expanded their ground operations on Hamas-run Gaza and stormed its main southern city. Gaza health officials say 16,248 people have been killed in Israel's attacks.
Hamas fighters who rampaged through Israeli towns on Oct. 7 killed 1,200 people and seized 240 hostages, according to Israel's tally. More than 100 hostages were freed during the truce.
During the fundraiser, Biden said: "Everyone still being held hostage by Hamas need to be returned to their families immediately. We're not going to stop."
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