Israeli PM Ehud Olmert has said an army artillery barrage that killed 18 Palestinians in the Gaza Strip was the result of a "technical failure".
Many of the bodies were draped in the yellow flags of Fatah
He said troops had targeted an orange grove from which rockets had been fired on Wednesday, but instead hit homes in the northern town of Beit Hanoun.
The victims, including several children and women, were buried in Beit Hanoun on Thursday amid emotional scenes.
Palestinian officials described the killings as a massacre.
"I'm very uncomfortable with this event. I'm very distressed, Mr Olmert was quoted as saying by the Associated Press news agency..
"I checked it and I verified it. This is not the policy," he said.
GAZA DEAD SINCE END OF JUNE
Total: 247 fatalities
155 civilian deaths
57 deaths of children
996 wounded, including 337 children (34%)
Source: Physicians for Human Rights (28 June to 27 Oct)
But military operations against suspected Palestinian militants would continue, he added, admitting that further mistakes "may happen".
Mr Olmert repeated recent offers to hold talks with Palestinian Authority President Mahmoud Abbas.
Artillery fire in Gaza has been suspended until an inquiry was complete into Wednesday's shelling, the Israeli army said.
Israel launched its operation in and around Beit Hanoun last month in an effort to root out militants firing rockets.
Calls for revenge
Tens of thousands of Palestinians attended the funeral of those who died in the Israeli shelling on Wednesday.
The deaths were caused when what witnesses described as a volley of tank shells hit a built-up civilian area. Many of the dead were from one extended family.
During the funerals, one man carried the bodies of two babies, wrapped in traditional burial shrouds.
Mourners cried out and chanted anti-Israeli and anti-US slogans as the procession moved through the streets.
"This town has known many black days and this is just one more, perhaps the blackest of them all," Beit Hanoun pharmacist Tayseer al-Masry, 36, told AFP news agency.
Outside Gaza there was widespread criticism of the Israeli strike.
France and Russia warned against an escalation of hostilities, while the UK foreign secretary, Margaret Beckett, said it was "hard to justify" the Israeli action.
In the US, the White House and the state department called for restraint from Palestinians.
Palestinian President Mahmoud Abbas has already described the killings as a massacre, and demanded intervention by the United Nations.
He held a telephone conversation on Thursday with exiled Hamas leader Khaled Meshaal, in an effort to restart talks on a Palestinian government of national unity.
The UN Security Council discussed the violence in Gaza on Thursday.