Hamas leader Yahya Sinwar may have given the order to execute all remaining Israeli hostages in Gaza in the event of his death, according to one of Israel’s leading hostage negotiators.

“It is a moment of either opportunity or a moment of doom,” said Gershon Baskin, the negotiator who oversaw the release of Sinwar, together with 1,026 other Palestinian prisoners, in 2011 in return for the kidnapped Israeli soldier Gilad Shilat.

“A moment of doom because there are rumours that Sinwar instructed people holding hostages that, should he be killed, they should kill their hostages,” he added.

Sinwar was killed last Wednesday in a chance encounter with the Israel Defense Forces (IDF) in southern Gaza.

At the time of his death, 101 Israeli hostages were being held captive in the enclave, at least 60 of whom were thought to be alive.

Their predicament may be further complicated by the fact that the Hamas fighters who hold them are now being led by Sinwar’s younger brother Muhammad.

Mr Baskin said it was not possible to confirm the rumours of a kill order or, if it existed, whether it had already been enforced.

However, he said the rumour should be taken “seriously”, citing the six hostages who were killed in late August after the IDF closed in on the tunnel in which they were being held.

“We saw the six hostages killed when Israel was entering the tunnel. That could be the case now. We just don’t know,” he said.