The turmoil in the wake of Fatah's shock election defeat to Hamas erupted as supreme leader Khaled Meshaal promised the Islamist faction would implement reform and work with the international community following its surprise victory in Wednesday's parliamentary poll.
Hamas's landslide victory, winning 76 seats in the 132-member parliament, has decisively ended Fatah's decades-long grip on politics, alarmed the West and thrown into turmoil international hopes of bringing peace to the region.
With Hamas to face the daunting task of forming a new Palestinian government, Israel's Defence Minister Shaul Mofaz said their leaders would be accorded no immunity if they persist in violent attacks.
Several thousands Fatah party supporters, joined by dozens of masked militants demonstrated in the West Bank, demanding that its central committee resign and that the faction boycott participation in any Hamas-led government.
Hundreds more Fatah supporters, including security officers, barged into the Gaza Strip's parliamentary compound, firing into the air, before marching through the streets towards Palestinian leader Mahmud Abbas's Gaza home.
In the West Bank town of Ramallah, 40 gunmen climbed onto the roof of the parliament, firing into the air to demand that Fatah leaders resign, before hundreds of sympathisers marched to the Palestinian leadership compound.
They erected a Palestinian flag, a yellow Fatah banner and a picture of their late leader, Yasser Arafat, on the roof of the Palestinian Legislative Council, furious over their humiliating defeat.
Around 3,000 supporters of Fatah also took to the streets in the troubled northern West Bank town of Nablus to demand the party leadership resign or else be "punished", and to boycott any new Hamas-led government.
About 80 masked Al-Aqsa militants fired rounds into the air and vowed that they would no longer adhere to a de facto Palestinian truce in attacks on
Israel. The truce officially expired at the end of 2005.
"Our bullets will go to the head of the occupation and the head of those who hurt the Fatah movement," a masked militant shouted through a megaphone.
A further 1,000 marched through the streets of Tulkarem, calling on Fatah's central committee to resign and for the party not to enter a coalition with
Hamas.
Fatah failed to get a single MP elected in the city's constituency.
Faced with the protests, re-elected Fatah MP and former deputy premier
Nabil Shaath said security forces would uphold public order and that a new central committee and revolutionary council would be re-elected in due course.
"The security organisations will handle any excesses that might lead to a breach of security," he told a Gaza City news conference. "We will not bow to any attempt to make chaos or create a situation which is undemocratic... which threatens public safety.”
The supreme leader of Hamas, who lives in exile in Syria following an
Israeli attempt to assassinate him, announced in Damascus that his movement would prove as effective in politics and reform as in fighting Israel.
He said Hamas would take account of realities in its approach to Israel, work with the international community and absorb its armed wing, although there was no question of reversing its non-recognition of the Jewish state.
"We have succeeded in the resistance and we will succeed in politics, reforms and change," Mr Meshaal told a news conference in Damascus.
He maintained resistance would continue to be the "legitimate right" of the Palestinians and scoffed at US threats to cut Palestinian aid in the wake of the Hamas victory.
"We are ready to work with Europe and even the United States if they wish," he said, suggesting that Hamas's armed wing be absorbed into a united Palestinian army if the international community wants the movement to disarm.
Israel, which pulled out of Hamas's Gaza Strip stronghold last year, has steadfastly rejected talks with the movement which refuses to recognise the
Jewish state's right to exist and has carried out scores of suicide attacks.
"Those at the top of a terrorist organisation and those who continue to carry out attacks against the State of Israel will not have immunity," Mr Mofaz told army radio.
During Mr Mofaz's tenure, the military has carried out targeted killings of Hamas militants and leaders.