Punishment beatings are often carried out in public as a deterrent
With talks aimed at bringing an end to the split between the rival Palestinian factions continuing in Cairo, BBC correspondent Aleem Maqbool reports on grave accusations of politically-motivated violence and abuse exchanged between the two sides.
"Mahmoud" is 23. His life is dominated by the fear that at any time he could be assaulted or even killed by Hamas, the faction which controls Gaza. He does not want his real name to be known for fear of retribution.
He walks with great difficulty and a pronounced limp. We enter his simple breeze-block home in Gaza, the place where, he says, he has recently been threatened by masked gunmen.
Mahmoud describes how, on one occasion, he was ambushed in the street, and shot repeatedly in both legs. It was because he was a militant loyal to Fatah, the faction in control of the West Bank.
He admits he beat Hamas supporters in the past, when Fatah was in charge in Gaza, but stresses he would never have used the methods that were used on him.
He pulls up his trousers to reveal horrifically scarred calves missing entire muscle groups.
"How can you reconcile with the person that attacked you and ended any hopes you had?" he asks.
"If God gives me strength, I'll shoot the one who shot me, and make him suffer the way I've suffered."
I'll shoot the one who shot me, and make him suffer the way I've suffered
Mahmoud, Fatah supporter
Human rights groups say Mahmoud's experience is far from unique.
Disturbing mobile phone footage we obtained shows a man, blindfolded and bound, having his legs broken with a club, over and over again.
He was left writhing on the ground in a public square after what is believed to have been a Hamas punishment beating.
Fatah supporters in Gaza say they are being persecuted for their political views, although the reason publicly given by their alleged tormentors is often a different one: collaborating with Israel, or drug-dealing.
But it is not just Hamas that is thought to be abusing its power.
In the West Bank, the Palestinian Authority (PA) is in charge. Its security forces are loyal to president Mahmoud Abbas of Fatah.
They have been accused of grave human rights violations, too. Human rights groups say they have been arresting, beating and torturing Hamas supporters.
At his home in Nablus, "Abu Moaz", not his real name, tells me that during his six months' captivity in a PA prison, he was often strung up to the ceiling by his wrists, which were tied behind his back, and beaten until he lost consciousness.
What they did to me was worse than a horror movie
Abu Moaz, Hamas supporter
He says his guards told him the beatings were a punishment for supporting Hamas, and that they wanted him to confess that the party was plotting to take over the West Bank.
Abu Moaz says he told them he knew of no such plan, and that he was nothing more than a political supporter of Hamas. But the torture continued. Abu Moaz suspects his captors were just using it as a brutal deterrent.
He says that, when he was finally released without a charge, the guards told him that if he told anyone what had happened, he would be arrested again.
"What they did to me was worse than a horror movie," he says.
"It's so painful that this was done not by my enemy, but by my own people."
When we put his case to Lt Gen Adnan Dameri from the Palestinian security forces, we were told that they did not detain people for their politicial views.
"There is no policy of using torture or violence against those who're accused," he stressed.
"If an individual security officer does this, and there's a complaint against him, he will be tried in accordance with the law."
Hamas has issued similar statements in the Gaza Strip saying arrests are only made for criminal reasons and to maintain security.
'Cycle of abuse'
Aleem Maqbool's report from Gaza and the West Bank
However, Randa Siniora, Director of the Palestinian Independent Commission for Human Rights, says both sides have clear cases to answer.
Her organisation was set up to address human rights abuses committed by Israel, but has increasingly had to investigate cases of violence by Palestinians against Palestinians.
She says these abuses have continued even in the face of Israel's massive offensive in Gaza.
"It is saddening that even when the [Israeli] aggression was going on, serious breaches [of human rights] were being committed by the internal security forces in Gaza," she says.
"When it comes to cases of disappearances in Gaza, or cases of torture and arbitrary arrests in the West Bank and Gaza, the human rights situation is not very promising."
Until now, psychiatrists working at a torture rehabilitation centre in Ramallah have predominantly had to deal with people affected by their treatment in Israeli jails.
They have noticed that their patients find it harder to come to terms with abuse at the hands of fellow Palestinians.
They also report a trend developing where torturers who were themselves abused in Israeli prisons now act out that abuse on others.
Palestinians in the West Bank and Gaza Strip are hoping a political deal between the rival factions will put an end to the violence.
However, the number of people already affected, and their potential desire for vengeance could prove a major obstacle to healing the rifts.
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