Fighting has broken out in the Gaza Strip for a second day, with two people killed and at least 10 wounded as rival Palestinian factions exchanged fire.
A truce agreed late on Sunday between Fatah and Hamas was broken just hours after it came into effect.
Senior official Saeb Erekat said if the violence was allowed to continue there was no point in having a government.
Sunday's violence was the worst in a single day since the two sides agreed to form a unity government in February.
Five people were killed and 18 injured.
Egyptian mediators brokered an agreement between the factions to pull their armed men off the streets, dismantle roadblocks and return a number of hostages taken on Sunday.
The truce was intended to come into effect at 0100 on Monday (2200 GMT Sunday) but within hours fighting had broken out, with both sides claiming the other had attacked its members.
Mr Erekat described the violence, together with the abduction of BBC journalist Alan Johnston nine weeks ago, as "despicable scenes".
"I am ashamed as a Palestinian this morning to see the continuation of such chaos. If the government cannot deliver on this one authority, one gun, the rule of law, I believe there is no purpose to have a government," he told the BBC.
"Society can't stand - no social fabric can be maintained if you have multiple authorities and multiple guns.
"Any society, any society on the earth must understand that the one authority, the one gun, the rule of law is the essence of society. And that's it - this is absent now from Gaza."
Sunday's violence began when a leader of the Fatah-linked al-Aqsa Martyrs' Brigades was ambushed and shot dead.
The death of Baha Abu Jarab sparked a series of factional clashes.
His driver also died in the ambush, which the Brigades blamed on the armed wing of Hamas.
Hamas denied the claim, but two Palestinians reportedly linked to Hamas were later killed near a mosque in Gaza City, and nine more people were injured, many of them members of Hamas.
Later, three people were wounded during Abu Jarab's funeral procession in Jabaliya, witnesses said.
Sunday's fighting was the worst outbreak of violence since a February ceasefire between the rival factions, who established a unity government in March.
Up to 400 people have died in clashes between the two factions since the Islamist Hamas won last year's parliamentary elections.
Last week, Hamas and Fatah launched a major security operation to crack down on the violence and lawlessness.
Officials said troops loyal to both Fatah and Hamas would now wear the same police uniform and answer to the interior ministry, which has been placed under the control of Hani Qawasmi, a political independent in the coalition government.
Since the Israeli withdrawal from Gaza in 2005, the strip has seen a wave of infighting, armed robberies, deadly family feuds and kidnappings.