RAMALLAH, West Bank - All Palestinian prisoners must be released as part of any peace deal with Israel, Palestinian President Mahmoud Abbas said in a televised speech Thursday to mark Palestinian Prisoners' Day.

About 8,500 Palestinian prisoners are currently held by Israel, according to the Israeli human rights group B'Tselem.

Israeli and Palestinian negotiators are trying to reach a peace deal by the end of the year. Months of meetings have not yielded visible progress. The release of prisoners is a key Palestinian demand, as many families have members in prison.

"We can't achieve peace with Israel without releasing all the prisoners and detainees in the prisons of occupation," Abbas said. "There will be no signing of any agreement that does not include the release of all of them."

Palestinians consider the prisoners as heroes in their struggle for statehood. To many Israelis, the prisoners are terrorists out to destroy the Jewish state. Since peace talks began, Israel has released scores of prisoners, most of whom had almost finished their sentences. Palestinians consider the releases disappointing, and have asked for the release of veteran inmates.

Two years ago, Hamas militants in Gaza kidnapped an Israeli soldier in a bold cross-border attack. Corp. Gilad Shalit remains in captivity, and Egyptian-brokered talks over a prisoner swap were put on hold many times.

Rallies were held across the West Bank on Thursday to call for the release of the prisoners. Palestinian officials, including Prime Minister Salam Fayyad, attended the gatherings.

The Ramallah rally drew hundreds of Fatah supporters, who raised Palestinian flags and carried the picture of the most prominent imprisoned Fatah leader, Marwan Barghouti.

Walid Abu Mohsein, 40, marched for his brother, Jamal, who has served 17 years of a life term for killing an Israeli. "He believes in peace," Abu Mohsein said of his brother. "Israel is not giving him a chance to prove that he now supports peace."