Eight Palestinians were killed and at least 50, including many civilians, were injured in Gaza yesterday in the worst outbreak of violence between Hamas and Fatah since the legislative elections last January.
The running gun battles in Gaza City between forces of Hamas and those loyal to the President, Mahmoud Abbas, came after the virtual collapse of talks on a putative "national unity" coalition government.
They also follow six months of mounting tensions aggravated by the non-payment of salaries to Palestinian Authority employees because of the international economic blockade imposed on Hamas for refusing to recognise Israel.
The fighting overshadowed the possibility that Israel would escalate its three-and-a-half-month military operations against Palestinian militants in Gaza. Dan Halutz, the Israeli chief of staff, said that discussions were under way on "a more continued and deeper ground action" as one means of halting Qassam rocket attacks on the Negev border town of Sderot.
The Palestinian violence will also be the backdrop to a visit to the region by Condoleezza Rice, the US Secretary of State.
Ms Rice is expected to promote proposals for using Mr Abbas's presidential guard to provide security at the Karni crossing between Israel and Gaza, whose frequent closures have helped to bring the economy to near-collapse. Israeli officials said they hoped to discuss ways of boosting Mr Abbas's standing as a counterweight to Hamas.
The most serious exchanges of fire took place near the parliament building in Gaza City and close to the official residence of Mr Abbas, who was not in Gaza. After a crowd of anti-Hamas demonstrators grew to include hundreds of police and civilians, the pro-Hamas militiamen ordered by the Interior Minister, Said Siyam, to quell such protests opened fire. Theyexchanged fire on two of Gaza's main streets, mainly with Fatah security personnel. As Hamas Radio accused Mr Abbas of fomenting Palestinian unrest, Tawfiq Abu Khoussa, a Fatah spokesman, accused Hamas of "shedding Palestinian blood" and using excessive force.
The Palestinian Prime Minister Ismail Haniyeh called for an end to the violence, and criticised the military for their role in the fighting. His views were echoed by Mr Abbas, who said the violence was unacceptable.
"These confrontations have crossed the red line, which we have avoided crossing for four decades," he said in a speech from the Jordanian capital, Amman. "I instruct the attorney general to begin an investigation and those involved will be prosecuted."