A newly released Palestinian prisoner (L) is greeted upon his arrival to the West Bank city of Ramallah December 18, 2011. [Photo/Agencies]

JERUSALEM - Israeli authorities on Sunday night released 550 Palestinians in the second half of a prisoner swap with Hamas.

Two months ago, Israel freed 477 Palestinian prisoners in the Egyptian-brokered deal reached in Cairo, to gain the release of Gilad Shalit, who has been held captive by Hamas militants for over five years.

Four hundred of the detainees have served more than two thirds of their sentences, with over 300 of them to have been released by the end of the year.

Among those to be released Sunday is a Hamas militant with "blood on his hands" - Israel's term referring to militants who either directly took part in or planned attacks against Israelis, who had mistakenly been excluded from the previous release, a source close to the Israeli government told Xinhua.

Most of the detainees to go free belong to Palestinian National Authority President Mahmoud Abbas' Fatah faction, and are considered less dangerous than the Hamas members, many of whom were jailed for multiple life sentences for terror attacks against civilians.

The Israeli Supreme Court on Friday dismissed petitions by opponents of the release, who said the prisoners' having taken part in shooting, bombing, and firebombing attacks against Israelis should disqualify them from release.

Some 40 detainees were released to Gaza, two to East Jerusalem, two to Jordan, and the remainder to the West Bank.