The Al-Qassam Brigades, the armed wing of Hamas, announced his death at a time when Israel and Hamas are following a 42-day ceasefire which began on January 19.

In a statement, Abu Obeida, spokesperson for the brigades, also confirmed that Marwan Issa, Al-Qassam's deputy chief of staff, had been killed.

"The enemy has assassinated two of our great leaders, but their legacy and resistance will continue," Obeida said in the statement as quoted by Xinhua news agency.

Israel, earlier, said Mohammed Deif was one of the key architects behind the October 7, 2023 attacks in southern Israel which left at least 1200 people dead.

The Hamas had taken 251 people as hostage during the attack.

Deif was known to have helped engineer the construction of tunnels that have allowed Hamas fighters to enter Israel from Gaza. He was also credited with designing Hamas's signature weapon, the Qassam rocket, reported BBC.

Hamas releases eight more hostages

Meanwhile, Hamas freed eight hostages on Thursday, the latest release by the group since the Gaza ceasefire began on January 19.

Israel released 110 Palestinian prisoners in exchange for the eight hostages.

The released hostages included five Thai nationals.

Sharing  details, the Israel Defense Forces wrote on X: "After 482 days, 8 hostages that were held captive by Hamas and Islamic Jihad terrorists in Gaza finally returned to Israel."

Apart from the five Thai nationals, three Israelis were also released in the third phase of the exchange.

According to reports, the release process was delayed due to chaos since a crowd of Palestinians surrounded and jeered at hostages as they were turned over to the Red Cross.

The five Thai nationals were identified as Thenna, Sathian, Sriaoun, Seathao and Rumnao.

Agam Berger, an IDF soldier, was released from northern Gaza.

The other two Israeli nationals freed during Thursday's exchange were identified as Gad Moshe Mozes and Arbel Yehud.