GAZA, Oct. 12 (Xinhua) -- Izz el-Deen al-Qassam Brigades, armed wing of the ruling Hamas movement, threatened on Thursday to use "unconventional force" against Israeli troops if the Gaza Strip was invaded.

    When asked about whether Hamas militia is working on developing and producing weapons in the besieged Gaza Strip, the group's spokesman Abu Obaida did not deny.

    Abu Obaida's threat came as the Israeli troops carried out limited incursions and ground operations into several parts of Gaza Strip, especially the areas near Gaza-Israel border.

    "The attempts to reoccupy Gaza come as a bid by the Israeli army to cover up its failure in restoring captive soldier Gilad Shalit," Abu Obaida said.

    Three Palestinian groups headed by Izz el-Deen al-Qassam Brigades abducted Shalit in a cross-border raid on an Israeli post in southern Gaza Strip on June 25 and has held him hostage so far.

    Israel launched a massive offensive in Gaza three days after the abduction and continued it for almost four months in a bid to bring back the abducted soldier.

    On early Thursday, four Palestinian militants and one civilian were killed by Israeli troops, which was operating in the Gaza Strip. Enditem