Palestinian Prime Minister Ismail Haniya has accepted the resignation of his interior minister following a new wave of factional fighting in Gaza.
Hani Qawasmi offered to resign last month in protest at worsening security, but was persuaded to stay on.
Seven people have been killed in two days of violence in Gaza, the worst since Hamas and Fatah agreed to form a unity government in February.
Independent Mr Qawasmi was given the key post after months of wrangling.
Officials are quoted as saying Mr Haniya will take over the interior portfolio.
Correspondents say the resignation casts serious doubts about the power-sharing partnership between the Islamist Hamas and the secular Fatah group.
Surge of violence
Former academic Mr Qawasmi was to have overseen Palestinian security services, but was reported to have faced competition from powerful Fatah rivals for control of armed factions.
A Hamas government spokesman said Mr Qawasmi resigned because he had not been informed of a security deployment last week billed as an attempt to quell the unrest.
Sunday's violence - with five dead and 18 injured - was the worst in a single day since February.
Egyptian mediators brokered a deal to get armed men off the streets and have hostages released, but fighting erupted again within hours.
Two people were killed and at least 10 wounded as rival factions exchanged fire on Monday morning.
Up to 400 people have died in clashes between the two factions since the militant Hamas movement won last year's parliamentary elections.
Senior Palestinian negotiator Saeb 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."
Since the Israeli withdrawal from Gaza in 2005, the strip has seen a wave of infighting, armed robberies, deadly family feuds and kidnappings.