"This is another instance of Hamas fake news," said Lieutenant Colonel Jonathan Conricus, an army spokesman, referring to the Palestinian Islamist movement which runs the Gaza Strip.

"We got reports... from a doctor that said that the baby had a preexisting heart condition and that was most likely the cause of death," he told AFP, without naming the physician or explaining how the information was obtained.

"We don't have any additional evidence, the body of that poor baby is in Gaza... There is no way of finding out for sure," Conricus said.

The Hamas health ministry in Gaza reiterated on Friday that eight-month-old Leila al-Ghandour died after inhaling tear gas along the Israeli border on Monday as protests escalated into the deaths of 60 Palestinians, almost all killed by army gunfire.

"Did she suffer from another illness? We are waiting for the medical examiner to complete his report which could come on Sunday," said its spokesman, Ashraf al-Qudra.

The baby's family has blamed the Israeli army for her death, while explaining that Leila had been at the scene of the border protests because of a misunderstanding between the child's teenage mother and a brother.

A spokesman for the justice ministry in Gaza City said an investigation was being carried out into the death of Leila, who was buried on Tuesday, as was customary for all deaths.

In Geneva on Friday, the UN Human Rights Council voted to send a team of international war crimes investigators to probe the deadly shootings of Gaza protesters by Israeli forces.

Israel has justified its actions, arguing the measures were necessary to stop mass infiltrations from the blockaded Palestinian enclave.