Hundreds of unemployed Palestinians clashed with security forces for a second day in the town of Khan Yunis in the Gaza Strip.
The clashes underline the security challenge facing Palestinian leaders
Witnesses say the protesters threw missiles and fire bombs while police used tear gas and fired into the air.
Officials say at least 10 people, police and protesters, were injured.
Unemployment has been rife in Gaza since the intifada started five years ago and Israel closed the borders to Palestinian workers.
Reports say the demonstrators are angry about the planned introduction of state school tuition fees.
The clashes highlight the chronic problem of poverty in Gaza and the challenge facing the Palestinian Authority to impose order after years of military raids by Israel.
In a separate development, the Israeli army has given Palestinian security officers a tour of the evacuated settlements in Gaza prior to next week's handover.
It was a rare example of on-the-ground security co-operation between the two sides, correspondents said, as well as first time Palestinian officials have entered the former enclaves.
Palestinians are waiting to take control of the evacuated settlements
Israeli officials say the tour was intended to allow the Palestinians to plan their troop deployments.
Israel - which says it expects to complete its pull-out by 15 September - has finished its demolition of private houses in the settlements.
Israeli officials say Egyptian troops are expected to be deployed on the Egyptian side of the Gaza border in the next few days.
The question of who controls Palestinians and goods entering Gaza from other countries has not yet been agreed.
Israel says it wants to continue to monitor them, but the Palestinians say that would make Gaza a large prison.
Israel - which has occupied the Gaza Strip since 1967 - evacuated its 8,500 settlers there last month as part of a unilateral "disengagement" from the conflict with the Palestinians.
Egypt has not commented on statements by Israeli officials that President Hosni Mubarak is expected to make his second visit to the Jewish state in November.
Foreign Minister Silvan Shalom said the visit was likely to coincide with events marking the 10th anniversary of the assassination of Prime Minister Yitzhak Rabin - but would also have "bilateral implications".