"The (military) is in a very high state of readiness in all arenas, in defence and offence," army spokesman Daniel Hagari told reporters without directly commenting on Aruri's killing.

"We are highly prepared for any scenario.

"The most important thing to say tonight is that we are focused and remain focused on fighting Hamas."

Asked earlier about the strike that killed Aruri, the Israeli military said it "does not comment on foreign media reports".

Two Lebanese security officials told AFP that Aruri was killed by an Israeli strike in a southern Beirut stronghold of Hamas ally Hezbollah.

Hamas later confirmed Aruri's death, which Lebanese state media said came in an Israeli drone strike that killed a total of six people.

Aruri is accused by Israel of masterminding numerous attacks.

He was elected deputy to Hamas chief Ismail Haniyeh in 2017, before being officially named the group's number two.