Thousands of Palestinians have staged marches in the Gaza Strip in protest at a new reform of the security services.
Militants are vying for power ahead of Israel's planned withdrawal
They said the choice of Palestinian leader Yasser Arafat's nephew Musa as public security chief would do nothing to end corruption or promote change.
Many of the marchers were armed, and included representatives of Mr Arafat's Fatah movement.
The reform reduces the number of security branches from eight to three, as demanded by international mediators.
It comes as an effort to resolve a political crisis within the Palestinian Authority caused by a spate of kidnappings in Gaza on Friday.
Mr Arafat announced the overhaul after Prime Minister Ahmed Qurei described the security situation in Gaza as "a real disaster, a real catastrophe, and an unprecedented lawlessness".
Mr Qurei tendered his resignation and that of his government, but Mr Arafat rejected the move.
But the prime minister is not keen to withdraw his resignation, Jamal Shubaki, Minister of Local Government said.
Palestinian officials are holding a series of emergency talks and meetings in an attempt to resolve the leadership crisis.
The Palestinian government is to meet on Monday.
A state of emergency remains in force in Gaza.
All this poses a serious challenge for Mr Arafat and many Palestinian officials fear that they may be facing a period of prolonged political instability, says the BBC's David Chazan in Jerusalem.
But the man who has come to symbolise the Palestinian struggle is holding on to the leadership, our correspondent says.
And many Palestinian commentators expect that he will survive this crisis as he has so many others in the past.
During Saturday's protests, more than 2,000 Palestinians gathered in front of the Legislative Council headquarters in Gaza City and shouted slogans denouncing the new appointments, particularly that of Musa Arafat.
"We don't agree with your decisions and we don't agree with the appointments," they shouted.
"It's not acceptable to fight corruption with more corruption. It's forbidden to change one corrupt man for another," said Samir Mashrawi, a member of Mr Arafat's Fatah movement.
In a separate move, the al-Aqsa Martyrs' Brigade, an armed group linked to Fatah, issued a statement rejecting the appointment of Musa Arafat, which they described as "a dangerous sign" that opened the way for power struggles.
Arafat has been under pressure to reform security
Demonstrations also took place in the southern city of Khan Yunis, where protesters set fire to a Palestinian security post.
Also as part of the security overhaul, Maj Gen Saeb al-Ajez replaced Ghazi Jabali - the Gaza police chief who was among those kidnapped on Friday.
His abductors, Jenin Martyrs' Brigades, had demanded that he be investigated in connection with corruption allegations.
The others kidnapped on Friday were four French aid workers and another Palestinian official, Colonel Khaled Abu al-Ula. They have all been released.
A period of political instability that could lead to a worsening of security in Gaza appears inevitable, says our Jerusalem correspondent.
Lawlessness has been increasing as militant groups appear to be trying to strengthen their positions before a planned Israeli withdrawal from Gaza, our correspondent says.
That, combined with a lack of clear directives from Mr Arafat, has led to the prime minister's strong language, he says.
Mr Qurei wants Mr Arafat to grant him more powers to deal with the worsening security situation.