After pre-dawn Muslim prayers on Monday, eight buses sped out of the gates of the Ketziot jail in Israel's Negev desert. Handcuffed prisoners smiled from the windows.
Some knelt in prayer before transferring to Palestinian buses for the trip home to tearful reunions with family and friends, some waving Palestinian flags.
The freeing of 500 prisoners comes a day after Israel's cabinet approved a plan to withdraw from the Gaza Strip.
Palestinians say Abbas needs large-scale prisoner releases to get resistance groups to formalise the ceasefire he agreed on with Israeli Prime Minister Ariel Sharon at an 8 February summit.
About 8000 Palestinians are held by Israel.
The prisoners were freed after 5am (0800 GMT) at several crossing points to the West Bank and Gaza in the biggest release since 1996, when 800 people were freed. Those making the longest journey left the prison first.
Palestinian prisoners show their
relief at being released
None of the prisoners - the first of 900 to be freed in coming weeks - had been found guilty of attacks that killed or wounded Israelis. Most had already served at least two-thirds of their sentences.
The director of Aljazeera's office in Palestine, Walid al-Umari in Ram Allah, said the detainees included 118 political and administrative detainees, who had been arrested without charge. The rest had been convicted, but most of them had almost finished their sentences.
Muhammad Dahlan, a close Abbas adviser set to be confirmed as minister for cabinet affairs later on Monday, said Palestinians awaited a wider release.
Palestinians want those who carried out attacks resisting the Israeli occupation to be included in future releases.
Tel Aviv has so far ruled out freeing prisoners they describe as having "blood on their hands".
About half the prisoners to be freed on Monday are from Fatah. The rest are from Islamic resistance groups that are still weighing up whether to formally agree to the ceasefire.
Happy but worried
"We are very happy, but at the same time worried and sad," Nasir Abu Aziz, a released member of the Palestinian National Council told Aljazeera.net. "We are happy to be released, but sad for our brothers inside the Israeli jails."
About 8000 Palestinians are
being held by Israel
"We want to deliver a message to the international community and the Palestinian Authority. They should do their best to release all detainees who were jailed before the signing of Oslo Accord," he said.
Abu Aziz went on to say that the Israeli conditions for releasing Palestinian detainees will never serve the peace process.
"Release of Palestinian detainees should not come as an Israeli goodwill gesture. We want them to end this issue for ever."
Speaking to Aljazeera's correspondent in Jenin, Ata Abu Rumaila, Secretary General of the Fatah movement in Jenin, said: "What has been carried out is an Israeli deceptive trick against our people.
"The Israelis are trying to use the Palestinian emotions towards the detainees and apply the [truce] agreement according to their own standards, thus violating it," he added.
Abbas' internal position was strengthened by Fatah's naming of key loyalists in the new cabinet list to be passed on Monday.
They are due to carry out his mandate to ensure resistance fighters are brought on board and implement reforms to the ailing Palestinian Authority.
A new government list had been expected since Abbas was elected in January after Yasir Arafat's death, but insiders said it was held up by disagreements between him and Prime Minister Ahmad Quraya.
On Sunday night, 16 Palestinians who were deported from the West Bank to Gaza for political reasons were released by Israel but they faced initial problems while trying to cross the Erez border from Gaza.
"A Palestinian source we have interviewed said the problem has been solved and that the Israeli side agreed to let the deportees return along with their families," said Aljazeera correspondent Shirin Abu Akla.
Sixteen Palestinian deportees
returned to the West Bank
The 16 deportees were accompanied by their families so the number of the returned deportees reached 51 Palestinians, she added.
Israel is due to allow the return of 20 other Palestinians expelled to Gaza in 2002 after a siege of the Church of the Nativity in the southern West Bank town of Bethlehem, Defence Minister Shaul Mofaz has said.
The correspondent added that the Israeli side had said the return of the Nativity Church's deportees was related to handing over security of the town of Bethlehem to Palestinians, which would be studied later.