Palestinian factions have clashed in the West Bank and Gaza Strip, despite pledges to end a new wave of violence.  The new Palestinian government, led by the Islamic militant group Hamas, is facing a growing challenge from Fatah, the party that has dominated Palestinian politics for decades.

Gunmen from the ruling Hamas movement and the rival Fatah party exchanged fire at the Health Ministry in the Gaza Strip, as a Palestinian power struggle erupted into a second day of violence. There was a similar incident in the West Bank town of Nablus, where dozens of Fatah gunmen took over the municipality building, and ordered the mayor, who is from Hamas, to shut down his offices.

Tensions escalated Thursday, when moderate Palestinian President Mahmoud Abbas of Fatah blocked an attempt by Hamas to gain control of the security forces. The sides traded accusations, and after clashes Saturday, Fatah officials warned that there was a danger of civil war.

That prompted leaders of both sides to hold an emergency meeting, in which they agreed to settle their differences peacefully.

"There will not be a civil war," Jibril Rajoub, a Fatah strongman in the West Bank, told Israel Radio. He said the two sides have no choice but to co-exist as brothers and avoid violence.

But Palestinian analyst Wadia Abu Nasser is not so sure.

"I believe that there will be some clashes here and there, but I am not seeing a civil war yet. And I highlight the word 'yet' because it might take place, but within [a] few months to come," said Nasser.

Even though Hamas won January elections by a landslide, the group is facing a growing challenge from Mr. Abbas, who was elected separately a year earlier. He wants to revive the peace process with Israel, while Hamas seeks the destruction of the Jewish state.

Hamas' position has prompted the United States and Europe to cut off nearly a billion dollars in annual aid to the Palestinian Authority. Mr. Abbas believes the militant policies of Hamas are leading the Palestinians to international isolation, and he is working to limit the powers of the new government.