Gunmen killed a Fatah activist and wounded three others Monday evening, one of several shootouts between the rival groups in northern Gaza that also left at least seven other people injured.
In addition, Fatah charged that Hamas militants had attacked one of its charities, and each group accused the other of abducting its members. Sufian abu Zaida, a former Cabinet minister from Fatah, was briefly held by Hamas gunmen and later freed unharmed in return for a promise to release a Hamas activist.
Early today, a member of Hamas' security force was killed and more than a dozen people were injured during a gun battle at the main hospital in Gaza City. Hamas said its officers, who maintain a post on the grounds of Shifa Hospital, came under fire from national intelligence officers loyal to Palestinian Authority President Mahmoud Abbas.
The outbreaks threatened to shatter a truce forged after factional violence Sunday killed three people and seemed to confirm fears that Abbas' call for new elections could ignite wider civil conflict.
On Monday, Abbas, who belongs to Fatah, said the climate remained "dangerous." But he insisted that he would proceed with early presidential and parliamentary elections next year if the two sides remained stuck over formation of a government to replace the one run by Hamas.
"The people cannot go on for long. The people are suffering," Abbas told reporters in the West Bank city of Ramallah after meeting with British Prime Minister Tony Blair.
At a news conference, Abbas and Blair urged the international community to redouble efforts to promote a comprehensive Middle East peace agreement.
Blair praised Abbas' call for early elections as a way to get around the factional standoff and end a months-long international aid embargo against the Hamas-led government.
"We want to work with people of moderation and tolerance," Blair said.
The British prime minister called for fresh international efforts to support Abbas, a relative moderate, and to ease the economic plight of Palestinians, beset by the aid cutoff.
Blair said he hoped an initiative would emerge in coming weeks aimed at reviving a peace process that has been dormant since soon after the outbreak of the Palestinian intifada, or uprising, in September 2000. An Abbas aide said the discussion between the two leaders did not delve into specifics.
Hamas accused Blair of interfering in internal Palestinian matters, highlighting the political risk to Abbas of being characterized by foes as a tool of the West and Israel.
Ahmed Yousef, a top advisor to Palestinian Authority Prime Minister Ismail Haniyeh, called for new talks on a possible ruling coalition that would avert elections, which Hamas views as illegal.
Abbas again left the door open to a possible agreement on forming a government that would be suitable to the West and bring an end to the crippling aid cutoff. He said that was the best way out of the deadlock.
The United States and European Union consider Hamas a terrorist group and halted aid after it defeated Fatah in parliamentary elections in January. The West has demanded that the Palestinian government recognize Israel, renounce violence and abide by past IsraeliPalestinian agreements.
Hamas' refusal has been the main obstacle to a powersharing arrangement despite months of negotiations between Abbas and the militant Islamic group's leadership. Declaring those talks at a dead end, Abbas announced Saturday that he would call elections, though he did not set a date.
Abbas' announcement on elections sparked a day of disorder Sunday that was extraordinary even for the violence-plagued Gaza Strip. Gunmen attacked a training camp of his presidential guard, killing one officer, and later fired mortar rounds at the presidential compound. Abbas was in the West Bank at the time.
Meanwhile on Sunday, the convoy of Foreign Minister Mahmoud Zahar, a Hamas leader, came under fire. The group called it an assassination attempt.
Blair met later with Israeli Prime Minister Ehud Olmert.
Special correspondents Rushdi abu Alouf in Gaza City and Maher Abukhater in Ramallah contributed to this report.