Armed and masked Palestinian Hamas militants man a makeshift checkpoint in the streets of Gaza City, 2 Feb 2007

Escalating violence between rival Palestinian factions Hamas and Fatah has killed at least 17 people in the Gaza Strip Friday.

Hamas and Fatah officials announced that they had agreed to a new ceasefire, but it is not clear if any new deal will hold. Previous ceasefires have quickly collapsed.

Two senior Fatah officials were among those killed Friday.

This latest unrest comes one day after a days-old Egyptian-brokered ceasefire collapsed. Six people were killed in violence Thursday.

Hamas militants attacked President Mahmoud Abbas' Gaza offices and a radio station of his Fatah movement. Fatah also attacked the Hamas-affiliated Islamic University for the second day.

President Abbas has appealed for calm and urged all parties to stop the violence.

Palestinian officials say Mr. Abbas and the top leader of Hamas, Khaled Mashaal, plan to meet in Saudi Arabia next week in another effort to bridge their differences and negotiate a unity government.

Meanwhile, Israeli troops killed four Palestinians in two separate clashes near the city of Ramallah in the West Bank.

Two members of the Palestinian Preventive Security Service loyal to Mr. Abbas were killed in the town of Bitounia. Two other Palestinians were killed when Israeli troops fired on their vehicle. The Israeli military says the vehicle was transporting weapons.

Some information for this report was provided by AFP, AP and Reuters.