JERUSALEM - A senior Israeli official said Sunday that the nation must move to release its most prominent Palestinian prisoner - Fatah leader Marwan Barghouti.

Barghouti is serving five life sentences in an Israeli prison after being convicted of involvement in fatal attacks on Israelis.

As the West Bank leader of the Fatah movement of President Mahmoud Abbas, Barghouti is the highest Palestinian official in Israeli hands.

Ynet, the Web site of the Yediot Ahronot newspaper, quoted Deputy Defense Minister Ephraim Sneh as telling an independent security group that "Barghouti is the most popular leader among the Palestinians. We also helped him gain that position. There are legal obstacles to releasing him, but we will have to solve them."

Sneh did not indicate when this should be done.

Before the current Palestinian uprising began in 2000, Barghouti was seen as a moderating influence among Palestinians, pushing for peace talks and a Palestinian state next to Israel. Israeli peace activists met with him frequently.

However, in the two years before he was captured by Israeli forces in 2002, he advocated violent resistance against Israelis in the West Bank.

Israel's official position is that Barghouti cannot be released because he fits the category of prisoners with "blood on their hands," or those with direct involvement in terror attacks. However, some exceptions have been made in the past.

Since Barghouti was convicted in a civilian court, his release would require a pardon from Israel's president.

Israel and the Palestinians are locked in negotiations to free an Israeli soldier captured in June in a cross-border raid by Hamas-linked militants from Gaza. Hamas has demanded freedom for more than 1,000 prisoners in exchange for the soldier.