Palestinian Authority President Mahmoud Abbas has canceled an appearance at a rally celebrating Israel's withdrawal from the Gaza Strip.
An aide told the Associated Press Mr. Abbas was concerned about the presence of gunmen in the crowd.
Organizers said the rally at an abandoned Jewish settlement in Gaza had been called to show unity among rival militant groups and support for the Palestinian Authority.
Earlier Wednesday, a top aide to Mr. Abbas said the Palestinian leader will demand that armed militants disarm immediately after parliamentary elections early next year.
A short while later, leaders of Hamas, Islamic Jihad and the Democratic Front for the Liberation of Palestine denounced the plan and said they would not cooperate.
Meanwhile, Palestinian police have begun sealing the Gaza-Egyptian border, to stop Palestinian revelers from crossing into Egypt.