Gaza government officials declared Wednesday a day of mourning, with a collective funeral in central Gaza City at midday, for the four civilians and four militants killed by Israeli fire a day earlier.

Officials called on residents of Gaza to join the funeral procession.

In Moscow, President Mahmoud Abbas asked the Russian foreign minister to exert pressure on Israel, and demand a halt to what he described as an "escalation" against Gaza.

PLO Executive Committee Member in Gaza Zakariyya Al-Agha condemned the deaths as a "massacre" of the Ash-Shuja'iyya neighborhood, saying in a statement that the deaths "translated into deeds the Israeli minister's remarks threatening another Cast Lead."

Israel's opposition Chairwoman Tzipi Livni said Saturday that the time had come for a fresh military campaign against Gaza, in the wake of a barrage of 50 projectiles which landed in the western Negev, causing no damage or injuries.

"The right way to deal with it is with force, just like Israel did during and after Operation Cast Lead," Israeli news website Ynet quoted Livni telling Gaza-vicinity Israeli local authority heads.

In January, Gaza's main militant factions confirmed a year-old truce with Israel, after weeks of increased rocket fire and spiraling tensions along the border prompted a warning from Arab leaders that Gaza was risking a major new Israeli invasion.

Abbas told reporters in Moscow that "there has always been an Israeli escalation in Gaza, West Bank, and Jerusalem," adding that the latest instance of escalation "should not be a reason not to achieve national unity."