Israeli aircraft fired missiles at open areas in northern Gaza early Saturday and ground troops set up a second artillery battery near the coastal strip — part of an intensifying campaign against Palestinian rocket fire on Israeli border areas. Israeli air strikes have killed eight Palestinians in Gaza this week, including a fighter whose car was struck Friday evening, while he was on a mission to fire rockets. Palestinian Interior Minister Nasser Yousef told his security chiefs that "firm and serious action" would be taken against facilities used to manufacture or store weapons, his office said in a statement released Saturday. But there was no talk of disarming factions, as Israel has demanded, and the statement said Palestinian security forces "would not enter any house looking for weapons." In Israel, Vice Premier Shimon Peres warned it would be a serious mistake to sideline Mahmoud Abbas, signalling growing disagreement within the Israeli government over how to deal with the Palestinian leader. Peres spoke after Prime Minister Ariel Sharon announced he would shun Abbas until he cracks down on factions, and Defence Minister Shaul Mofaz said Abbas was too weak and isolated to negotiate a peace deal. The Sharon government's criticism of Abbas is unprecedented, but it remains unclear whether it signals a shift in policy. The international community has urged Israel to work with Abbas, a moderate who opposes violence but also refuses to disarm groups by force, citing fear of civil war. Peres said Israel could not afford to marginalise Abbas. "When you say there is no partner, then only one partner is left, the terrorists. This is a mistake of the first order," Peres told Israel Radio.