Macron condemns 'unacceptable blackmail' by Hamas with Gaza hostages

French President Emmanuel Macron Tuesday denounced "unacceptable blackmail" by Hamas after the Palestinian militant group threatened to execute some of the around 150 hostages it abducted in a weekend assault.

"The blackmail by Hamas after its terrorist acts is odious and unacceptable," Macron told reporters on a visit to Germany.

The French president added that he considered it "likely" that Hamas had had outside "help" in its onslaught against Israel.

But he stressed there was "no formal trace" of any "direct involvement" by Iran, at a joint news conference with German Chancellor Olaf Scholz.

Supreme leader Ayatollah Ali Khamenei earlier Tuesday denied any Iranian involvement in Hamas's shock weekend attack on Israel despite its strong support for the Palestinian militant group.

Hamas said Monday that Israeli air strikes had killed four of its hostages, and later warned it could start killing them itself.

"Every targeting of our people without warning will be met with the execution of one of the civilian hostages," Hamas armed wing, the Ezzedine al-Qassam Brigades, said in a statement.