Hamas named its Gaza leader Yahya Sinwar as successor to former political chief Ismail Haniyeh, who was assassinated in Tehran last week, the group said, in a move that reinforces the radical path pursued since the Oct. 7 attack on Israel.

Sinwar, the architect of the most devastating attack on Israel in decades, has been in hiding in Gaza, defying Israeli attempts to kill him since the start of the war.

"The Islamic Resistance Movement Hamas announces the selection of Commander Yahya Sinwar as the head of the political bureau of the movement, succeeding the martyr Commander Ismail Haniyeh, may Allah have mercy on him," the movement said in a brief statement.

News of the appointment, which came as Israel braces for a likely attack from Iran following the killing of Haniyeh in Tehran, was greeted with a salvo of rockets from Gaza from the bands of militants still fighting Israeli troops in the besieged enclave.

"The appointment means that Israel needs to face Sinwar over a solution to Gaza war," said a regional diplomat familiar with the talks brokered by Egypt and Qatar, which are aimed at bringing a halt to the fighting in Gaza and a return of 115 Israeli and foreign hostages still held in the enclave.

"It is a message of toughness and it is uncompromising."

Sinwar, who spent half his adult life in Israeli prisons, was the most powerful Hamas leader left alive following the assassination of Haniyeh, which has left the region on the brink of a wider regional conflict after Iran vowed harsh retaliation.

Israel has not claimed responsibility for the assassination but it has said it killed other senior leaders, including Hamas deputy leader Saleh al-Arouri, who was killed in Beirut, and Mohammed Deif, the movement's military commander.

Born in a refugee camp in the southern Gaza city of Khan Younis, Sinwar, 61, was elected as Hamas' leader in Gaza in 2017 after gaining a reputation as a ruthless enforcer among Palestinians and an implacable enemy of Israel.

Israel's chief military spokesman, Rear Admiral Daniel Hagari, blamed Sinwar for the Oct 7 attack and said Israel would continue to pursue him.

"There is only one place for Yahya Sinwar, and it is beside Mohammed Deif and the rest of the Oct 7th terrorists," he told Al-Arabiya television, according to a statement released by the military. "That is the only place we're preparing and intending for him."