Thousands of angry Hamas loyalists on Sunday marched at the funeral of a Muslim preacher who died in the custody of government interrogators, accusing the Palestinian Authority of killing the man and turning the ceremony into a rare show of defiance against President Mahmoud Abbas.

The demonstration was an unusual sight in the West Bank, where Abbas' Palestinian Authority has become increasingly autocratic since his Hamas rivals seized power in the Gaza Strip in June. Since then, police have cracked down on protests perceived to challenge Abbas' rule.

Also Sunday, Israeli officials pointed to incremental progress in peace talks with Palestinians — appointing of joint committees to deal with secondary issues like water, the environment, economic and judicial matters. However, both sides said this was far from a breakthrough, because core issues like

Jerusalem, Palestinian refugees and final borders were not involved.

Addressing an economic conference in Saudi Arabia Sunday, Palestinian Prime Minister Salam Fayyad appealed for Arab support. He also put some blame on Israel for the failure of the Abbas regime to show a strong presence on the ground in the West Bank.

"Israel continues to raid our cities, undermining the credibility of our forces in the eyes of the population and demoralizing them," Fayyad's office quoted him as saying. He also criticized Israel's blockade on Gaza.

In Gaza, Hamas was planning a mass march on an Israeli crossing for Monday to protest the blockade. Israel's military was preparing to prevent Palestinians from crashing through as they did last month on the Egypt-Gaza border.

The noisy funeral showed that the Islamic militant Hamas is a force in the West Bank, though Abbas is in control, his regime indirectly bolstered by Israeli forces who regularly operate against Hamas and other militant groups.

Some 3,000 Hamas loyalists crowded the village of Kobar, carrying the body of 44-year-old Majed Barghouti, who died in a lockup run by intelligence officials on Friday, a week after he was arrested. Hamas officials said they did not trust a government investigation announced by Abbas.

Mourners waved the green flags of the militant Muslim group as they carried Barghouti's body, boldly chanting in support of Hamas and its armed wing, the Qassam Brigades, a group banned in the West Bank. At a separate nearby march for women, mourners wrapped green Hamas bandannas around their headscarves and loudly condemned Abbas' intelligence chief, Tawfik Tirawi, whom they blamed for Barghouti's death.

"Tirawi, you are a coward, you are the Americans' deputy," the women chanted. "We will crush your head, collaborator," they said. Tirawi did not respond to requests for comment Sunday.

Barghouti had an inflamed liver and a serious heart problem when he died, said Justice Minister Ali Khashan. He could not say if the man died because of mistreatment sustained in detention, but said "individual" cases of torture are dealt with swiftly. Khashan declined to discuss Barghouti's case because of the ongoing investigation.

Hamas spokesman Taher Nunu swiftly dismissed the investigation. "He was tortured to death," Nunu told a news conference in Gaza. Nunu called on Palestinians to disobey any orders by Abbas' government to arrest Hamas loyalists.

Barghouti, a father of eight, was a mosque preacher in Kobar and spent several years in Israeli prisons. He was among hundreds of Hamas activists detained by Abbas' security forces in the West Bank following the violent Hamas takeover of Gaza in June. Dozens remain in custody.

Four men who were arrested alongside Barghouti told his family that they were all tied up in painful positions during interrogation, and that intelligence officers demanded to know where the detainees had hidden weapons.

Shawan Jabareen, head of the Palestinian human rights group al-Haq, said Palestinian security forces routinely beat Hamas loyalists, who are arrested on suspicion of owning weapons or membership in the group's armed wing.

"Torture has become a phenomenon," Jabareen said. He said his group had documented some 120 cases of mistreatment in detention.

In a statement published in Palestinian newspapers, the intelligence service said Barghouti had complained of chest and abdominal pain and was examined by a hospital doctor two days before his death. Intelligence officials would not comment Sunday on the allegations.

A protest planned by Hamas loyalists in the West Bank town of Ramallah, where Abbas' government is headquartered, was quickly dispersed by club-swinging Palestinian police.