Israel's military says it has established the deaths of four more people abducted by Hamas on 7 October.
It says the four were killed while together during an Israeli operation in Khan Younis in southern Gaza, adding that their bodies were still being held by the militants, reports BBC.
The men were named as British-Israeli Nadav Popplewell, 51, Chaim Peri, 79, Yoram Metzger, 80, and Amiram Cooper, 85.
IDF spokesman Rear Adm Daniel Hagari said intelligence gathered in recent weeks had led to the assessment.
"We assess that the four of them were killed while together in the area of Khan Younis during our operation there against Hamas," he said, without giving further details.
Last month, Hamas claimed that Nadav Popplewell had died in an Israeli strike in April. The UK Foreign Office said it was investigating, but there was no confirmation of his death until now.
Hamas released a video showing the other three men in December.
All four hostages were kidnapped from kibbutzes near the Gaza Strip on 7 October.
In a statement via the Hostages and Missing Families Forum, relatives said news of the men's deaths should "lead every leader to profound soul-searching".
The statement added: "Chaim, Yoram, Amiram, and Nadav were kidnapped alive, some of them were with other hostages who returned in the previous deal - and they should have returned alive to their country and their families."
UK Foreign Secretary David Cameron said in a post on X that he was "greatly saddened" to hear about Nadav Popplewell's death. "My thoughts are with his loved ones at this terrible time for them," he added.
Nadav Popplewell was kidnapped at his home along with his mother, who was eventually released. His brother Roy was killed in the attack.
Hamas killed about 1,200 people and took 251 others hostage during its attacks on southern Israel, according to Israeli authorities.
The group released 105 civilians during a week-long truce in November.
About 120 hostages remain unaccounted for. Israeli officials have said many are presumed dead.
Israel launched a military campaign to destroy Hamas in response to the cross-border attack.
At least 36,470 people have been killed in Gaza in almost eight months of fighting, according to the Hamas-run health ministry.