BEIRUT, June 29 (Reuters) - Lebanon's Parliament Speaker Nabih Berri, a key ally of Hezbollah, on Monday slammed a U.S.-brokered agreement between Lebanon and Israel, warning it could lead to attempts to divide Lebanese and said it would not be implemented. In comments to Lebanon's al-Akhbar newspaper, Berri described Iran-U.S. negotiations as the only realistic opportunity to secure Israeli withdrawal from Lebanon and that any attempt to separate Lebanon from the U.S.-Iran track would prolong Israeli occupation.