Dahlan, 46, made the request on medical grounds, a senior official in his office. President Mahmound Abbas accepted his resignation, another senior Palestinian official said.
Dahlan was heavily criticized within Abbas's secular Fatah faction for the failure of his security forces to prevent Hamas seizing control of the Gaza Strip last month.
During the Gaza fighting, in which more than 100 people were killed, Dahlan was outside his native Gaza, sidelined by surgery on both knees which was performed in Germany.
During an interview with Reuters in the West Bank on June 19, Dahlan acknowledged mistakes and said individuals, including himself, should take responsibility for their errors.
Last month, another senior security official, Rashid Abu Shbak, was dismissed by Abbas.
Güncelleme Tarihi: 27 Temmuz 2007, 11:05