At least six people have been killed and about 100 more are said to have been wounded after gunfire erupted at a rally attended by Fatah supporters in Gaza.

Shooting broke out as tens of thousands of people were attending the rally in Gaza City on Monday to mark the death of Yasser Arafat, founder of the Palestine Liberation Organization (PLO).

Nour Odeh, Al Jazeera's correspondent in Gaza City, said that people fled from the scene as gun battles between Fatah and Hamas fighters intensified.

She said doctors at local hospital had been "overwhelmed" by casualties and that the death toll could rise.

Fatah officials accused Hamas forces of opening fire from the nearby Islamic University, but Hamas said its men had come under attack from Fatah fighters and shot back.

"Before the rally, Fatah militants were deployed throughout the area," said Ihab al-Ghosein, spokesman for the Hamas-controlled interior ministry.

"Fatah is responsible for continued incitement against the Palestinian police, and there was a clear attempt to bring back chaos."

Organizers say that about 100,000 people had turned up at the commemoration event.

Tense atmosphere

Hamas had broken up some smaller demonstrations organized by its rival on Sunday, the third anniversary of Arafat's death.

Speaking at Monday's rally before the gunfire broke out Odeh called the atmosphere in Gaza City "quite tense".

"Fatah promised everyone a show of force and presence in Gaza and a show of force they certainly did show," she said.

"[The rally] has surpassed all expectations [of the number of people attending]."

Hamas had set up checkpoints on the main north-south road in Gaza to check vehicles going to the event, residents said.

Their security forces also deployed across Gaza City and fired in the air on Monday morning at one intersection after youths threw stones at them, witnesses said.

Odeh said that she had spoken to people who had walked to the rally from Beit Hanoun, which lies at the northernmost tip of the Gaza Strip.

"Four months after the Hamas takeover of Gaza, the occasion of the anniversary of Yasser Arafat's passing has basically brought all Fatah members together to show that they are here," she said.

She said that the rally had galvanized Fatah supporters after previous attempts to hold public demonstrations in the Gaza Strip were put down by Hamas's police force.

Marginal presence

Fatah, a secular party, has had only a marginal presence in Gaza since Hamas forces violently took control of the region in June and took over key institutions.

The Wafa news agency, which is run by the office of Mahmoud Abbas, the leader of Fatah and the Palestinian president, said Hamas had confiscated pictures of Arafat and headdresses symbolizing the late leader.

The items were seized "at a time when the Gaza Strip is being deprived of basic goods and medicine", a Hamas security official was quoted as saying by a pro-Hamas website.

Israel recently imposed caps on fuel imports to the Gaza Strip, leading to transport restrictions and reductions in electricity output to the Palestinian territory.

As tensions spilled over between fellow Palestinians in Gaza, Abbas was in the Egyptian capital trying to win more support from Arab neighbors before the planned Annapolis peace conference in the US.

In Cairo, he met Hosni Mubarak, the Egyptian president, and Amr Moussa, the Arab League secretary-general, as well as the visiting foreign policy representative from the European Union.

Abbas then flew on to Turkey where he is scheduled to attend a summit on Tuesday with Recep Tayip Erdogan, the Turkish prime minister.

PHOTO CAPTION

The rally of Fatah supporters in Gaza