Missiles blew up two Palestinians in the Jabalya refugee camp in north Gaza on Thursday after most of the makeshift city was stormed by more than 200 tanks and troop carriers.
Helicopters backing a separate occupation force that swept into the Rafah refugee camp in Gaza's far south, also fired three missiles, killing a civilian in his 70s and two men, whom soldiers said were armed.
Witnesses said Israeli troops with armoured bulldozers also demolished about 20 houses before withdrawing.
Israeli forces frequently raze Palestinian buildings they say harbour resistance fighters who fire at them during their raids.
Meanwhile, the army's north Gaza incursion, its biggest inside the tiny territory since a Palestinian revolt began in 2000, has killed at least 43 unarmed civilians who were taking no part in the resistance.
Reacting to the 16-day raid, British Foreign Secretary Jack Straw condemned disproportionate Israeli violence that had killed 116 Palestinians.
In a statement released by his office, Straw condemned the particular case of a Palestinian schoolgirl who was shot 20 times after she had already been fatally wounded.
"Israel has an obligation under international law to ensure that its response to terrorism is proportionate to the threat it faces, as well as a duty to avoid innocent civilian casualties and humanitarian suffering. It is not meeting those obligations."
The EU also warned Tel Aviv it could face sanctions unless the Israeli-Palestinian conflict is resolved, a confidential Israeli government study said.
Ron Prushor, director-general of the Israeli foreign ministry, told Israeli army radio on Wednesday that many countries and organisations were also beginning to view Israel in the same way the South African apartheid regime was viewed.
"Israel has ... a duty to avoid innocent civilian casualties and humanitarian suffering. It is not meeting those obligations"
British foreign minister
Political sources said a 10-year forecast prepared by Israel's foreign ministry warns of increasing international isolation as the European Union grows more influential.
Lior Ben Dor, a spokesman for the Israeli foreign ministry, said the study was meant to be an "internal document" for the ministry's employees.
It examines future scenarios of the development of Israeli-European and Israeli-Russian relations and concludes that a politically and economically strong Europe will not be in Israel's interests.
The study also revealed that European youths were increasingly rejecting the existence of an exclusively Jewish state in Palestine, but envisioned a single multi-cultural entity.