The London-based Arabic newspaper reported Cmdr. Mohammed Deif of the Hamas military wing, Izz ad-Din al-Qassam Brigades, opposes the deal, Ynetnews.com said. He joins Hamas Politburo delegate Gaza Mahmoud al-Zahar in opposition to the agreement.
But Ahmed Jabari, head of Hamas' military wing in Gaza, is reportedly backing the deal.
Ynetnews.com said the rift in the Hamas military wing could affect the unity deal because the wing is considered the core of the Gaza Strip's security forces, many of which do not accept Abbas' authority as their prime minister.
The deal was signed last week between Hamas Politburo chief Khaled Mashaal and Abbas in Qatar.