Thousands of people took to the streets of the West Bank today for the funeral of Arafat Jaradat, a Palestinian who died in Israeli custody.
More than 10,000 Palestinians are estimated to have joined the funeral procession from Hebron to Sair, the village where 30-year-old Jaradat was from.
Israel's security forces were on high alert for fear of riots, according to Israeli newspaper Haaretz.
The armed wing of the Fatah movement, the al-Aqsa Martyrs Brigades, have vowed that "this horrific crime will not go unpunished."
Al Jazeera reported that members of the group were present at Jaradat's funeral, handing out leaflets promising to avenge him and firing rifles into the air.
BBC correspondent Jon Donnison tweeted this picture from the scene:
Body of Arafat Jaradat arrives in Sair amid huge crowds. twitter.com/JonDonnison/st…
— Jon Donnison (@JonDonnison) February 25, 2013
The West Bank had seen days of protests even before Jaradat's sudden death, as activists demanded the release of four Palestinian prisoners who are on long-term hunger strike.
The tension was heightened when Jaradat died in Israel's Meggido Prison on Saturday, in circumstances that are still disputed. The Israeli intelligence agency originally said that Jaradat had suffered a heart attack, while Palestinian officials allege that he was tortured under interrogation.
An autopsy was carried out on Sunday, but did not establish a cause of death. One Palestinian Authority pathologist who attended the post mortem said marks on Jaradat's body indicated abuse, yet the Israeli Health Ministry maintained that bruises to his chest were the result of efforts to resuscitate him.
Israeli authorities say their investigation is ongoing.
"The situation in the West Bank right now is about as volatile as it has been since the Second Intifada," said GlobalPost's senior correspondent in Jerusalem, Noga Tarnopolsky, referring to the widespread Palestinian uprising of about a decade ago.
Both Israeli and Palestinian observers say a "third intifada" could be imminent, in which both sides risk losing control of the security situation in the West Bank.
"Still, I have to say that I'm not sure there exists either the Palestinian political will, or muscle, to keep a real insurrection going, or that the citizenry is really about to blow up. No matter how you look at it, the Palestinians have a lot more to lose right now," Tarnopolsky added
Demonstrators clashed with security forces in Sair and Hebron on Sunday, while some 3,000 Palestinian prisoners staged a one-day hunger strike. Around 1,100 prisoners in Meggido Prison said they would also refuse food Monday and Tuesday, Haaretz reported.
Noga Tarnopolsky reported from Jerusalem. Follow her on Twitter @NTarnopolsky.