At the first working session of the parliament, Hamas voted to cancel all decisions made in the last session of the outgoing legislature. This includes additional powers given to Mahmoud Abbas, the Palestinian president.
Fatah legislators walked out in protest before Monday's vote was held. They had argued that Hamas was twisting the rules by holding the vote, and that the last session of the Fatah-controlled parliament was legal.
The vote set the tone for what legislators say will be a tension-fraught term, further dimming the possibility of the Fatah movement joining the Hamas government.
Fatah lawmakers insisted Hamas did not have the right to review the decisions. They were overruled by Hamas which controls an absolute majority in the 132-seat legislature.
Azzam al-Ahmad, a Fatah member of parliament, said his party would ask the Palestinian Supreme Court to overturn the decision.
"They [Hamas] are thirsty for power, and they can do what they want since they have a majority, but must do it according to the law," al-Ahmad said during a prayer break after the two-hour morning session.
"They (Hamas) are thirsty for power, and they can do what they want since they have a majority, but must do it according to the law"
Fatah member of parliament
During the debate, Abd al-Aziz Duaik, the parliament speaker from Hamas, repeatedly called al-Ahmad to order.
Mahmud al-Zahar, of Hamas, complained that "every time we present an important point, Azzam al-Ahmed would stand up and try to disrupt our work".
Al-Ahmad, who kept quoting from the Basic Law, the precursor to a Palestinian constitution, said: "I'm not disrupting your work. I am just presenting a legal point of view, and it's not my fault if you don't read."
Al-Zahar said coalition talks would wrap up this week, and that Hamas would then decide on the composition of its government.
Hamas had wanted to include Fatah, apparently in the hope of making the new government more palatable to the international community.
However, many in Fatah advocated staying in the opposition, with the expectation that a Hamas government faced with an international boycott and financial difficulties would quickly fail.