"This decision is unacceptable and illegal... The PLC (Palestinian parliament) is the only authority" which can decide on the programme of government, Sami Abu Zuhri, spokesman for the Islamist resistance movement, said on Wednesday.
The PLO had called on Hamas to alter its programme of government which fails to recognise the supremacy of the organisation.
Hamas is poised to form the next Palestinian cabinet after its landslide parliamentary election victory two months ago but its lineup must first win the approval of Mahmoud Abbas, the Palestinian Authority president and chairman of the PLO.
Hamas meanwhile moved a step closer to taking control of the Palestinian government, calling a special session of parliament to approve its new cabinet, sweeping aside objections from the Palestinian president over its refusal to recognise Israel.
Abbas plans to state his complaints, but in the end, he will give his blessing to the new Hamas governing team, an official said. After meeting Abbas, parliament speaker Abdel Aziz Duaik said the house would convene "early next week".
The Palestinian parliament is set
to approve the Hamas cabinet
Ismail Haniyeh, the incoming Palestinian prime minister, said in a statement that the parliament would be convened in special session to approve the new cabinet. The discussion may take several days, but the outcome is a foregone conclusion, since Hamas won 72 of the 132 seats in the 25 January parliamentary election, trouncing Abbas' Fatah.
Haniyeh is forming a cabinet with 24 Hamas activists and experts, after no other party agreed to join.
Saeb Erikat, a senior Fatah legislator, said Abbas planned to send Haniyeh a letter on Thursday expressing the PLO's reservations but authorising the Hamas leader to present his cabinet to the legislature this weekend.
"He will tell them that he will not obstruct their ability to go to the council with the cabinet," he said.
A top PLO official reaffirmed that regardless of Hamas's platform, the PLO would not hinder the formation of Haniyeh's cabinet.
"This (Hamas-led) government is legitimate and is based on a parliamentary majority at the PLC and would exercise its duties in accordance with the constitution," Salih Ra'fat, a PLO executive committee member, told Aljazeera.
"There will absolutely be no constitutional crisis," he said.
The PLO is an international umbrella group that represents nearly all Palestinian political factions, including the 3.8 million Palestinians of the West Bank, Gaza Strip and East Jerusalem and the 4.8 million-strong diaspora community spread around the world.
Founded in 1964, the PLO was led for over 30 years by the late Yasser Arafat, and the Fatah movement he led is the most powerful faction within the organisation.
The PLO became synonymous
with former leader Yasser Arafat
Internationally, the PLO is considered to be the legitimate representative of the Palestinian people and it holds a permanent observer seat in the United Nations General Assembly.
Hamas, whose charter calls for Israel's destruction, has never acknowledged the PLO as the sole official representative body of the Palestinian people. It considers the organisation to be redundant and calls for it to be remodelled.
The PLO is the signatory to interim peace deals with Israel which Hamas rejects.
Ahmad Qureia, the outgoing Palestinian prime minister, branded the Hamas platform "unacceptable" for not recognising the supremacy of the PLO.
"We cannot have a government that does not recognise the PLO," he said.
The refusal of Hamas to recognise the supremacy of the PLO was among the main factors behind the refusal of other Palestinian factions such as Fatah and the Popular Front for the Liberation of Palestine (PFLP) to join a Hamas-led coalition government despite nearly two months of negotiations.