Hamas militiamen on Monday violently dispersed a massive rally organized in the Gaza Strip by the rival Fatah movement. Six people were killed and 75 wounded, Palestinian officials said.

Fatah officials accused security forces controlled by Hamas, a radical Islamic movement, of committing a massacre against an unarmed crowd that was marking the third anniversary of the death of longtime Palestinian leader Yasser Arafat.

"This heinous crime is decisive evidence that the coup leadership of Hamas is out of step with the national values and customs and is using blind force and the most bloody and brutal techniques against our people in Gaza," said a statement released by the office of Palestinian Authority President Mahmoud Abbas, of Fatah.

Ehab Ghussein, spokesman for the Hamas-controlled Interior Ministry, said at a news conference in Gaza following the events that "armed men from the Fatah movement initially opened fire on the Palestinian masses in the rally so as to spread anarchy and chaos."

A Washington Post reporter on the scene saw no Fatah gunmen at the rally or in its vicinity. Other reporters gave similar accounts.

The crowd had assembled at Gaza City\'s Katiba Square. With estimates of its size running between 150,000 and 500,000, it was the largest Fatah rally since Hamas forcibly took control of the Gaza Strip in June. The size of the crowd showed the significant support Fatah retains in the strip, despite its loss to Hamas in January 2006 parliamentary elections in the Palestinian territories.

Participants waved yellow Fatah flags, flags of the Palestine Liberation Organization and pictures of Arafat, the late leader and symbol of Palestinian nationalism.

Local Fatah leader Ahmad Hilles told the crowd: "You affirm today that the Gaza Strip will remain Fatah\'s stronghold and will not be torched by the mutineers."

Palestine TV, controlled by the Fatah-dominated government based in the West Bank city of Ramallah, was broadcasting live from the rally when shots were heard. According to its report, Hamas militiamen fired into the crowd from the roof of Al-Azhar University.

Following the shooting, other Hamas militiamen moved in to arrest and beat people in the crowd, and ordered journalists not to film the event. Hamas security forces attacked some local journalists.

According to Muawiya Hassanain, director of emergency operations and ambulances with the Health Ministry, the six dead included a 14-year-old boy.

The al-Aqsa Martyrs Brigades, the armed wing of Fatah, accused Hamas militias of detaining 250 Fatah supporters, mostly young people, on their way home from the rally.

Jamal Zakout, an adviser to the Palestinian prime minister, said that "the people of Gaza went out to the streets to protect the heritage of Yasser Arafat and the national project and against the coup of the Hamas." He called on the Hamas leadership in Gaza to resign.

Mohammed Dahlan, who was Fatah\'s Gaza Strip strongman until being driven out by Hamas fighters in June, told Palestine TV, "Victory over those killers will be very soon through such rallies and gatherings."

Abbas has been using the third anniversary of Arafat\'s death to rally support on Palestinian streets. Thousands of people attended a Fatah-organized festival in Ramallah on Sunday, the actual anniversary.

The Palestinian National Liberation Movement, the full name of the Fatah organization, was established in 1959 by a cohort led by Arafat.

Sockol reported from Jerusalem, Kareem from Gaza.