The announcement was made through a video posted on their Telegram channel on Friday.
“Your army (the Israeli army) killed two hostages in the airstrike on Rafah a few days ago,” the group said.
The Al-Qassam Brigades further accused the Israeli military and government of deceiving the Israelis, saying: “Your army deceives you and continues to deceive you.”
“Your government (the Israeli government) only wants to recover the hostages in coffins,” it added.
The group did not reveal the identities of the captives or provide any images of them.
Israel has faced international condemnation amid its continued brutal offensive on Gaza since an Oct. 7, 2023 attack by Hamas despite a United Nations Security Council resolution demanding an immediate cease-fire.
Nearly 37,300 Palestinians have since been killed in Gaza, most of them women and children, and over 85,100 others injured, according to local health authorities.
Eight months into the Israeli war, vast tracts of Gaza lay in ruins amid a crippling blockade of food, clean water, and medicine.
Israel stands accused of genocide at the International Court of Justice, whose latest ruling ordered Tel Aviv to immediately halt its operation in the southern city of Rafah, where over a million Palestinians had sought refuge from the war before it was invaded on May 6.