The confirmation of Sinwar's death came in a video statement from Hamas' political leader Khalil al-Hayya, about 20 hours after Israel's Prime Minister Benjamin Netanyahu gave the same message.
In the video, al-Hayya also says that the hostages held by the group will not be released until there is an agreement on a ceasefire in the Gaza War.
Becoming "iconic"
Earlier in the day, Basem Naim, who is part of Hamas' political branch, claimed that the militant movement cannot be defeated – no matter how many leaders are killed.
Hamas is a liberation movement led by people who want freedom and dignity, and this cannot be eliminated, Naim told the AFP news agency.
He listed a number of leaders who have been killed recently and says that their deaths have only strengthened Hamas' popularity.
These leaders are becoming iconic for future generations' continued journey towards a free Palestine.
Killed bodyguard
Israel's military (IDF) also says it killed Mahmoud Hamdan on Friday, who Israel describes as Sinwar's bodyguard and responsible for killing six people from the hostage group. Intelligence previously suggested that Hamdan had likely been killed a few weeks ago, which turned out not to be true.
"Today, Mahmoud Hamdan was eliminated by the IDF during a clash with the military's soldiers, about 200 meters from the site where Sinwar was eliminated", the military writes on Telegram.
Ongoing attacks
During the night and Friday morning, new attacks on Gaza were reported, where Israel continues its raids a day after announcing that its military had killed Yahya Sinwar in an attack.
According to Gaza's rescue authority, several children were killed in attacks in the northern areas during the morning.
The operation in Jabalia in the north continues, the Israeli military announced in parallel. On Thursday, it was reported that over 20 people were killed in an Israeli drone attack on a school building.
The Gaza War began with Hamas' large-scale terrorist attack on Israel on October 7 last year, when hostages were also taken. During the war, over 42,000 people have been killed, according to figures from the health authorities in the Hamas-controlled area.