JERUSALEM, July 29 -- Human Rights Watch says Palestinian security forces in the West Bank and the Gaza Strip are responsible for human rights abuses including arbitrary arrests and torture, in a report planned for release on Wednesday.

"The political struggle between Hamas and Fatah has resulted in serious human rights violations in Gaza and the West Bank over the past year," said Joe Stork, deputy Middle East and North Africa director of Human Rights Watch, a U.S.-based advocacy group. "Security forces from both sides have targeted activists of the other party. Their abusive behavior has victimized Palestinians from all walks of life and weakened the rule of law."

In the West Bank, the security forces are run by the Fatah movement of Palestinian Authority President Mahmoud Abbas. Hamas, which won Palestinian elections in 2006, routed Fatah forces and took exclusive control of the Gaza Strip in June 2007 after a power-sharing deal collapsed.

The Human Rights Watch report echoes recent findings by al-Haq, a Palestinian human rights group based in the West Bank city of Ramallah. In a report released Monday, the group documented "acts of detention, torture and other cruel, inhuman and degrading treatment or punishment against civilians in the West Bank and Gaza Strip since June 2007."

Dmitri Diliani, a Fatah spokesman in Jerusalem, said there were "definitely abuses of human rights and we are committed to fixing them." But he added: "The violations in the West Bank stem from the fact that Israel has not permitted our security forces to train and has destroyed our police stations and jails. In Gaza, they stem from a military coup and a refusal to accept the other. It is a mistake to compare these two situations."

In Gaza, Hamas spokesman Fawzi Barhoum told the Associated Press that "mistakes" had been made by Hamas forces and that violators were being punished.

Human Rights Watch said that over the past year, Fatah-run security forces in the West Bank have arrested hundreds of Hamas members and supporters, detaining many without warrants and torturing prisoners under interrogation. The most common form of torture was forcing detainees to hold stress positions for prolonged periods, Human Rights Watch said.

The report found that Hamas forces in Gaza committed many of the same abuses and that three detainees died in custody in Gaza, apparently from torture.

Western nations have invested tens of millions of dollars in training Palestinian security forces in the West Bank. The United States has committed nearly $60 million to train the National Security Force and Presidential Guard loyal to Abbas. The report found that these security forces were not guilty of abuse and that most problems were associated with the Authority's Preventive Security force and General Intelligence Service. Human Rights Watch said further aid should be made contingent on improvements in these services.

Fred Abrahams, primary author of the report, said he had presented its findings to top officials in both the West Bank and Gaza.

"Officials on both sides listened to our concerns and said they would consider them. Each also said the violations were much worse on the other side," he said. "They said they do hold violators accountable, but those words are inconsistent with the facts on the ground."

Also in the West Bank, a 9-year-old Palestinian boy died Tuesday during clashes between Palestinian protesters and Israeli troops at a demonstration against what Israel calls its security barrier. Israel Television's Channel 10 reported that he had been shot by Israeli troops. An Israeli army spokesman said the circumstances of the boy's death are still unclear and the army is investigating.

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