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. 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 to be 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 militant 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 police who used batons to beat demonstrators. The Palestinian Authority has mostly forbidden any protests perceived to challenge Abbas' rule or to support Hamas in the West Bank. Police have used sticks, batons and fired in the air to disperse protesters and journalists covering the protests. In November, they shot dead a demonstrator in the southern West Bank town of Hebron who protested Abbas' peace negotiations with Israel. Hamas has been equally intolerant of opposition in the Gaza Strip. Two men have died in Hamas police custody in Gaza since June, both showing signs of suffocation. Eight demonstrators were shot to death in November during large protests in Gaza in support of Hamas' rival, Fatah.