Hezbollah leader Naim Qassem rejected a U.S.-brokered security agreement between Lebanon and Israel on Saturday a day after it was signed, describing it as a surrender to Israel.
The framework agreed on Friday provides for a phased Israeli withdrawal from some parts of southern Lebanon, alongside the deployment of the Lebanese army. But Israeli forces would be permitted to remain in an expanded security zone for the time being, pending further implementation.
In a statement, Qassem called it "null and void", and accused the Lebanese government of making unilateral concessions and undermining Lebanon's sovereignty.
He criticised provisions linking Israel's withdrawal to Hezbollah's disarmament, saying they effectively legitimised Israel's military presence and crossed "all red lines".
The group would continue its armed resistance, he added: "We did not leave the battlefield in the most difficult circumstances, and we will not leave it."
Qassem said the Iran-U.S. memorandum of understanding reached earlier this month, which guarantees Lebanon's territorial integrity, should serve as the basis for ending the conflict, rather than Friday's Washington agreement.
By Jana Choukeir, Eman Abouhassira and Pesha Magid