The army has told The Times that its report was flawed because it failed to mention two gunboat shells fired at about the time of the deaths. It insists, however, that they landed too far away to have been responsible.

Video footage of the anguished 11-year-old Huda Ghalia running between the corpses of her family on the beach at Sudaliya caused fury across the Arab world. Immediately the explosion Israel expressed regret and suspended all artillery fire — but never admitted responsibility.

On Tuesday the Israeli military issued the results of an investigation that exonerated itself. Officials said that the explosion could have been caused by a Palestinian landmine. “The accumulating evidence proves that [Friday’s] incident was not because of Israeli forces,” Amir Peretz, the Defence Minister, said.

Israel says that its land artillery batteries fired six shells at northern Gaza between 4.30pm and 4.48pm that afternoon, and that it can account for all but one, which was fired at 4.30pm. However, its investigation said that that shell was aimed too far away to have killed the Palestinians.

The investigation relies heavily on timing. It cites surveillance footage of the beach showing that it was quiet between 4.54 and 4.57pm, and film of ambulances apparently arriving at the scene at 5.15.

It says that the incident must therefore have happened between 4.57 and 5.10pm — at least nine minutes after it says it stopped firing land artillery.

But The Times has established that at 4.43pm the UN received a radio call from one of its officials in northern Gaza that said: “At 16.33hrs IDF artillery shelling has started again targeting the northern area, two artillery shells so far. One of the shells fell down at the coast west of the evacuated old Dugit settlement, some casualties among the people spending their day at the . . . ” Transmissions could be picked up by anyone with a scanner, which are widely available in Gaza.

Presented with the evidence of the UN transmission last night, Major-General Meir Kalifi, who led the Israeli investigation, insisted that the 4.33pm report was an earlier incident, near the abandoned settlement of Dugit. “[We] know of a request from the Red Cross to the Red Crescent at 4.30pm regarding one wounded individual along the beach. [We] believe that that is the case you are referring to,” General Kalifi said. “This is most likely in the Dugit area. Indeed they were shelling in the Dugit area, but the Dugit area was not near the incident. It was 700 metres away.”

However, Israeli military officials did concede that they made an error in the summary of the investigation’s conclusions concerning shells fired by ships. It cited General Kalifi as saying that all 17 naval shells were fired “approximately four hours before the incident”.

Israeli officials have now told The Times that two naval shells were fired at about the time of the deaths — at 4.24pm and 4.55pm — but that they were too far away to matter. Captain Jacob Dallal, an Israeli army spokesman, said: “The announcement was wrong. The announcement referred to the shells fired in the area of the incident before noon. We apologise.”

Palestinian hospital and ambulance records — some computerised, some handwritten and far from reliable — also contradict aspects of the Israeli chronology, as do survivor accounts. Those indicate that the fatal explosion may have happened before 4.54, when Israel’s aerial cameras were trained on the quiet beach. ()

The logs of Kamal Adwan hospital, in northern Gaza, also show that seven patients were admitted at 5.05pm, ten minutes before Israel says it filmed ambulances arriving.

DANGEROUS TIMES

16.30-16.48 Israel claims its ground batteries fired six shells. Investigation says all but the first at 16.30 are accounted for. Official investigation summary does not mention naval shells fired at 16.24 and 16.55, but officials say they are too far away to matter

16.43 Radio transmission from a UN field monitor in northern Gaza states: “At 16.33 IDF artillery shelling has started again targeting the northern area, two artillery shells so far. One of the shells fell down at the coast west of the evacuated old Dugit settlement, some casualties . . .”

16.57-17.10 The period when Israel says the picnickers must have died. This is based on film of beach between 16.54 and 16.57 apparently showing “nothing irregular”, on Palestinian reports of mass casualties at 17.12, and on a film showing ambulances arriving at 17.15

Additional reporting by Ian MacKinnon

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