Israel's military operation against Hezbollah began as a reply to the capture of two Israeli soldiers by the Lebanese militia on 12 July.
The campaign quickly grew into an all-out assault against Hezbollah, but the prisoner issue remains an emotive one among Israelis, Lebanese and Palestinians.
BBC News examines the prisoner issue at the heart of the current Middle East crisis.
The latest crisis in the Middle East flared on 25 June, when Corporal Gilad Shalit, 19, was seized by Palestinian militants who attacked an army position at Kerem Shalom, near the eastern edge of the Gaza Strip.
He was the first Israeli soldier captured by Palestinians since 1994. Hamas, which dominates the Palestinian Authority government, said it would consider releasing Cpl Shalit as part of a prisoner exchange. His whereabouts remain unknown.
Eldad Regev: captured by Hezbollah
Reservists Ehud Goldwasser, 31, from the northern coastal town of Nahariya, and Eldad Regev, 26, from the town of Kiryat Motzkin, were captured by Hezbollah on 12 July, prompting immediate Israeli military action. Little more has been heard about the pair since their capture.
Justifying its seizure of the two Israelis, Hezbollah said it mounted the raid in an effort to secure the release of Lebanese prisoners held in Israeli jails.
Although Israel holds thousands of what it calls security prisoners, most of those are Palestinian (see below). Following a major prisoner swap in early 2004, in which more than 400 prisoners were released to Hezbollah in exchange for a reservist colonel and the bodies of three Israeli soldiers, Israel now admits to holding just three Lebanese.
Chief among those is Samir Qantar, serving several life sentences for murder after attacking a civilian apartment block in Nahariya in 1979. A policeman, another man and his four-year-old daughter were killed. A baby girl was accidentally smothered by her mother as she hid in a cupboard.
Hezbollah leader Sheikh Hassan Nasrallah has frequently called for Qantar's release, threatening to derail the 2004 deal when he was excluded from the list of prisoners. His name has once again been raised during the current crisis. Israel has refused to discuss releasing Qantar, often linking his status to its search for information about Ron Arad, an Israeli airman missing since being shot down over Lebanon in 1986.
While in prison, Samir Qantar has grown in popularity
Israel also holds an Israel man of Lebanese descent, Nissim Nasser, arrested in 2002 and convicted of spying for Hezbollah. The third Lebanese prisoner is a fighter called Yehia Skaff, Hezbollah MP Nawar al-Sahili told the BBC. Mr al-Sahili said that Israel also holds a fourth man, a fisherman called Ali Faratan.
Israel is also thought to be holding 25 Lebanese citizens of Palestinian origin, many for conventional criminal offences. Their release is not understood to be at the heart of the dispute with Hezbollah.
Since the first Palestinian uprising began in 1987 the vast majority of security prisoners held in Israel have always been Palestinians. According to official figures supplied to the Israeli human rights organisation B'Tselem, 9,153 Palestinians are currently held by civilian and military authorities.
Of those, B'Tselem says 8,085 are held in civilian jails, 2,384 of them without charge. Some 645 are held under "administrative detention", without charge and often without knowledge of the suspicions against them. Among those in civil jails are 74 women and 265 under-18s.
Jailed Palestinian leaders often wield considerable influence
Although Israel's army is gradually transferring authority for jails over to civil authority, it still holds 1,078 prisoners, including 105 in administrative detention and 28 youths aged under 18, B'Tselem says.
Figures collated by Palestinians vary slightly from the Israeli tallies, but only slightly: the PLO's negotiations department says approximately 9,400 Palestinians are currently in all Israeli jails, with approximately 800 of those in administrative detention.
Those small differences are as close as the two sides come to agreement on the issue of prisoners. While Palestinian officials call their detainees "political prisoners", Israel says that some 70% of those behind bars have "blood on their hands".
Palestinian officials also criticise the conditions inside Israeli prisons, describing them as "far below minimum standards"; Israel's prison authority says its security prisoners receive the "highest level" of treatment.
The thousands of Palestinian prisoners play an important role in political life. Senior figures from the various Palestinian factions, such as Fatah's Marwan Barghouti, wield considerable influence from their cells on rank and file members on the street. The release of what Palestinians term "political prisoners" is a key demand of ordinary Palestinians and of their leaders.