Israel has an airtight case and was definitely not behind the explosion that caused the deaths of seven Palestinians last Friday on a Gaza Strip beach, Maj.-Gen. Meir Klifi, head of the IDF investigation into the incident, told The Jerusalem Post Wednesday. Klifi, who presented the exonerating findings to Defense Minister Amir Peretz Tuesday night, dismissed criticism from human rights activists in Gaza and from UN Secretary-General Kofi Annan, who said Wednesday that they found it "odd" that the explosion could have been caused by a Palestinian mine. "I can say definitively since I know for certain that an Israeli shell did not cause the incident," Klifi told the Post. Annan, at a press conference Tuesday before the IDF officially released its findings, was asked by a journalist about reports that Israel concluded the explosion was caused by a "mine that was on the beach, that sort of thing." Annan, in response, said, "To find a mine on the beach is rather odd." Diplomatic sources in Jerusalem expressed "disappointment" at Annan's comment, saying they would have expected the secretary-general of the UN would wait until after the IDF released the findings of its investigation before issuing any comment on the matter. Israel's ambassador to the UN, Danny Gillerman, was to meet Annan Wednesday evening in New York to discuss the matter. Officials in Jerusalem said, however, that there was no indication the UN had any intention of setting up an independent inquiry into the incident, as the Palestinians have proposed. Asked whether he thought an international investigation should be set up, Annan responded Tuesday that this would require the cooperation of the parties. Then, in an apparent reference to a failed attempt to set up an investigating committee in 2002 to look into Palestinian claims of a "massacre" in Jenin, Annan said, "Our previous attempts at such investigations were not too successful." Annan's spokesman, Stephane Dujarric, said Wednesday in New York that "at this point there are differing accounts of what happened, different investigations and we're watching this debate very closely." He denied, however, reports that Annan would send a "special envoy" to the PA to look into the incident. Referring directly to Annan's argument that it was difficult to believe the Palestinians had planted charges on a beach frequented by bathers, Klifi said he never declared that the explosion was caused by a bomb planted in the sand, just that the blast was unequivocally not caused by Israel. "I never said that I knew what caused the blast," he explained. "One of the possibilities that we raised is that it was an explosive device planted there. We need to keep in mind that this is not something new for the IDF, since in the past the Palestinians have planted bombs in places they thought the army would be." On Wednesday, Human Rights Watch military expert Marc Garlasco declared that he was certain the explosion was caused by an Israeli shell. The only question he said was whether the shell was planted in the beach by Palestinians or fired at the beach by the IDF. Garlasco backed up his conclusion with a claim that he found shell shrapnel 200 meters from the scene of the explosion. Klifi also dismissed this argument, claiming that the discovery of shrapnel 200 meters away fit in perfectly with his conclusion that Israel was not behind the incident. "He says that he collected shrapnel from 155 mm. shells 200 meters from the incident," Klifi explained. "I agree 100 percent with this, since there was a shell that landed 200 meters from the incident." Klifi did not comment on other of Garlasco's claims about the munition that killed the family, including nature of the wounds and the shape of the crater that the explosion left. But, he added, there was no way that an Israeli shell killed the seven. Klifi said that he was unaware of any requests by international bodies or other countries that had asked the IDF to review the findings of the investigation. He also said he planned to continue investigating the incident to try to uncover what had caused the explosion that killed the seven.