Israel holds roughly 11,000 Palestinian prisoners, many jailed in the past seven years of conflict.
Because so many Palestinians have relatives imprisoned in Israel, releases are seen by Israel as a way of swaying Palestinian opinion.
Last week, Olmert told members of his Kadima party that he would only release prisoners who are not serving time for attacks on Israelis, who identify with Abbas's government and who renounce violence
He said: "That is the only way to signal to Palestinian society that peacemaking and its culmination will yield results."
Miri Eisin, Olmert's spokeswoman, said on Sunday that all the prisoners who would be released would be fighters with more than a year left to serve.
Palestinians have long demanded that prisoners serving lengthy sentences be released, and that names be co-ordinated with the Palestinians through negotiations.
Ashraf Ajrami, the Palestinian minister of prisoner affairs, said: "If there was a large release of prisoners, it would support the Palestinian president and government, but when Israel makes unilateral moves, it does not do much to support President Abu Mazen [[Abbas] and the legitimate government.
"What Israel is doing is ignoring Palestinian demands."
Eisin said a special Israeli ministerial committee was to meet later on Sunday to decide on a final list of names.
Israelis will then have 48 hours to challenge the release in the country's supreme court.
Eisin said: "In theory, Tuesday night or Wednesday morning, you can release the prisoners."
Israel last released more than 250 prisoners in July.
Hamas accused Fatah of working hand in hand with Israel.
Sami Abu Zuhri, a Hamas spokesman, said: "The 100 Palestinian prisoners are from Fatah, and that means continuing discrimination against prisoners, with Fatah's agreement. It's dangerous ... when the occupation and Fatah play the same role in discriminating against the prisoners.
Olmert proposed the current release, timed to coincide with Ramadan, the Muslim holy fasting month, in his latest meeting with Abbas two weeks ago.
The recent meetings were intended to yield guidelines for peace talks that would culminate in a final peace accord and the establishment of a Palestinian state.
The objective is to formulate those guidelines by a US-sponsored peace conference tentatively scheduled in Washington in November.
The Palestinians are pressing for a more detailed document while Israel wants a vaguer text that will allow it more flexibility.