Scores of Fatah policemen who used to serve in the Palestinian Authority security forces in the Gaza Strip have now joined the al-Qaida-affiliated group calling itself the Army of Islam, sources in the Hamas-controlled Interior Ministry told The Jerusalem Post Thursday.

Meanwhile, Fatah's armed wing, the Aksa Martyrs Brigades, claimed responsibility for firing 20 rockets from the Gaza Strip recently. The group said the attacks signaled the beginning of a military campaign dubbed "Operation Gaza Autumn," in the course of which it would fire hundreds of rockets at Israeli communities. It said residents of Sderot had two choices: leave or die.

Fatah officials in Ramallah said they did not know if the threat by the Aksa Martyrs Brigades was genuine.

"We don't know what's happening in the Gaza Strip," a senior Fatah official said. "Ever since the Hamas coup last June, we have no idea what's happening on the ground."

The official, however, did not rule out the possibility that disgruntled Fatah activists were behind the recent spate of rocket attacks, or that some former Fatah-affiliated policemen had joined the Army of Islam.

According to the sources Hamas's Interior Ministry, dozens of Fatah-affiliated policemen who recently lost their jobs have joined the al-Qaida-linked group. The Army of Islam is headed by Abu Muhammad al-Ansari, who is also known as Mumtaz Dughmush.

Ansari is a former PA Preventive Security Service officer in the Gaza Strip. He belongs to the Dughmush clan, whose members have kidnapped several foreign nationals, including BBC reporter Alan Johnston, and bombed Internet cafes, hair salons and restaurants...