Gaza City  - At least 11 Palestinians were killed on Tuesday in a fresh outbreak of violent internecine clashes in the Gaza Strip, the worst in more than a month, security officials said.

The clashes erupted when Hamas police forces raided a neighbourhood in southern Gaza City before dawn, seeking to arrest members of a powerful local clan, the Dughmush.

One Hamas policeman and at least four members of the Dughmush family - three gunmen and a baby girl - were among the dead. Dozens were also injured in the clashes, in which both sides used rocket- propelled grenades and semi-automatic guns.

A statement by the Hamas-controlled Interior Ministry said the police forces killed three "wanted criminals" who refused to surrender during an attempt to arrest them.

The radical Islamist movement ruling Gaza ordered the overnight raid after one clan member killed a Hamas policeman and wounded another officer when police tried to arrest him near a Gaza City market on Monday.

Jameel Dugmush had escaped to the family's stronghold neighbourhood of al-Sabra, prompting Hamas to send its forces into the area.

Ihab al-Ghussein, a spokesman for the Hamas Interior Ministry, said "the security campaign in al-Sabra neighbourhood is over."

"All the wanted criminals were killed in the operation," he added in a statement sent to the media. "This was not a campaign against the Dugmush family. It only targeted some members of the family involved in security chaos."

The Dughmush family is known for being behind the so-called Army of Islam, a militant group which kidnapped BBC correspondent Alan Johnston in 2007.

It also took part in the June 2006 abduction of an Israeli soldier who is still being held in Gaza.

Hamas has accused the Army of Islam of trying to stir disorder in the strip on the order Hamas' bitter rival, the Fatah movement of Palestinian president Mahmoud Abbas.

Hamas says Abbas' movement, which is consolidating its power in the West Bank, is behind "attempts to shake security in Gaza."

The two Palestinian movements have severed all ties since Hamas violently seized sole control in the Gaza Strip in June 2007 by overpowering the headquarters of security forces loyal to Abbas.

Tuesday's clashes were the worst since early August, when a Hamas raid on the pro-Fatah Helles family in Gaza City's Sheja'eya neighbourhood left some 13 Palestinians dead and dozens more wounded. (dpa)