Israeli Prime Minister Benjamin Netanyahu said Thursday that reconciliation between Fatah and Hamas will make "peace much harder to achieve", hours after the Palestinian factions signed a unity deal.

"Reconciliation between Fatah and Hamas makes peace (with Israel) much harder to achieve," Netanyahu said on his office's Facebook page, accusing the Islamist movement Hamas of supporting violence.

"Reconciling with mass-murderers is part of the problem, not part of the solution. Say yes to peace and no to joining hands with Hamas," he said after the unity deal signed in Cairo.