An Israeli investigation into what caused an explosion on a Gaza beach that killed eight Palestinians will conclude that the blast was most likely caused by a mine planted by Palestinian militants and not an Israeli shell, military officials said Tuesday.

An elderly Palestinian man holds a picture Monday, June 12, 2006, showing Palestinian girl Houda Ghalia mourning over the body of her dead father, who was killed when an artillery barrage struck a family picnic on a Gaza beach Friday, June 9, 2006, killing eight Palestinian civilians, during a sit-in, in protest against the shelling, at the Ein-el-Hilweh Palestinian refugee camp, near the southern city of Sidon, Lebanon. Houda Ghalia was the only member of her family that survived the attack. [AP]

The Palestinians had blamed an Israeli shell for the killing of the civilians in the northern Gaza Strip on Friday, and had recognized as a hero a Palestinian girl whose image was broadcast around the world crying over her father's body at the scene.

While Israel had originally left open the possibility that it was responsible and expressed sorrow for the deaths, senior officials had suggested that Palestinian militants could have planted explosives on the beach and the army opened an investigation.

The military committee looking into the blast is expected to issue its findings later Tuesday.

The committee will announce that Israel was almost certainly not involved in the explosion and it was caused by explosives planted by the Hamas militant group, military officials said on condition of anonymity since the results were not official yet.

The blast occurred on the outskirts of the town of Beit Lahia, not far from where Palestinian militants frequently fire rockets toward Israel. Israel often shoots artillery in the area to prevent the rocket launchings.

According to the findings, shrapnel taken from two wounded Palestinians who were evacuated to Israeli hospitals showed that the explosives were not made in Israel, the officials said. In addition, the last Israeli shell fired toward Palestinian rocket launchers who operate in the area was seven minutes before the blast and landed 250 yards from the scene, the officials said.

Also, after the blast, Israeli military viewed Hamas militants collecting the shrapnel from the area, in an apparent effort to prevent authorities from revealing that the explosion was caused by explosives it had laid, the officials said.

The results of the investigation are also based on threats by Hamas to stop Israeli naval commandos from landing on the beach after group militants were killed in the area in an ambush by Israeli navy divers last month, the officials said.

The army has accounted for five of six of the shells that it fired in the area Friday evening before the blast, the officials said. The one shell that is not accounted for was fired before the five others - more than ten minutes before the blast that killed the Palestinians - and apparently landed further away than the shells that were fired later, the officials said.