GAZA (Reuters) - Fourteen-year-old Mohammad Ayoub ignored his mother’s objection and slipped away to join this week’s protest along the Gaza-Israel border, just hours after Israel’s military dropped leaflets in his Gaza village warning residents to stay away.

The mother of Mohammed Ayoub, 14, a Palestinian boy who was shot dead by Israeli troops during clashes at the Israel-Gaza border, shows her son's photo at her house in the northern Gaza Strip April 21, 2018. REUTERS/Mohammed Salem

A few hours later, the teenager was killed by an Israeli bullet to the head, Palestinian health officials said.

“He asked his aunt to tell me he would be back in an hour,” said his mother, Raeda, who instead buried her son late on Friday.

His death brought to 35 the number of Palestinians killed since border clashes intensified on March 30 in an ongoing protest known as “The Great March of Return” - evoking a longtime call for refugees to regain ancestral homes in what is now Israel.

For a month, clashes had erupted at the demonstrations and Israeli soldiers had used live fire to keep Palestinian crowds away from its border fence.

On Friday, Ayoub had been among the thousands who gathered to protest, some of whom used catapults and sling-shots to launch stones at Israeli forces, hurled burning tyres and tried to damage the fence.

Israel says it is doing what it must to defend its borders and accuses Hamas, the Islamist militant group which rules Gaza, of staging riots and using the crowds as cover to try to carry out attacks. Hamas denies this.

Israel’s use of live fire has drawn international criticism and Ayoub’s death received special attention.

“It is outrageous to shoot at children! How does the killing of a child in Gaza today help peace? It doesn’t! It fuels anger and breeds more killing. Children must be protected from violence, not exposed to it,” U.N. Middle East envoy Nickolay Mladenov wrote on Twitter.

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U.S. Middle East envoy Jason Greenblatt put out his own tweet: “A full investigation by Israel of Mohammed Ayoub’s death is underway so that we will be able to understand what happened. As we mourn the tragic loss of a young life, we must all resolve to avoid causing more suffering by responses to his death.”

An Israeli military spokeswoman would not comment on whether an investigation had been opened.

Ayoub’s family said friends of their son told them he was not among stone throwers.

TIGHT CONTROL

The protests are expected to peak in mid-May when, according to Hamas leader Ismail Haniyeh, the Gaza scenes would be replicated elsewhere on Israel’s frontiers.

Israel’s defense minister on Saturday said the leaders of Hamas bore responsibility for Ayoub’s death.

“Those cowardly leaders who hide behind woman and children and send them forward as human shields so they can continue to dig tunnels and carry out acts of terror against Israel,” said Avigdor Lieberman.

Hamas, designated a terrorist group by many Western countries, denies this.

More than two million Palestinians are packed into the narrow coastal enclave. Israel withdrew its troops and settlers from Gaza in 2005 but maintains tight control of its land and sea borders. Egypt also restricts movement in and out of Gaza on its border.

Matthias Schmale, the Gaza director of operations of the United Nations Relief and Works Agency (UNRWA), which provides aid to over half of Gaza’s population, said Ayoub was the third student of U.N.-run schools to be killed in recent weeks.

“Deeply disturbing news that child killed yesterday was yet another student at UNRWA school - two others were killed previously,” Schamale wrote on Twitter. “Children should never be targets.”