The Elders group of past and present world leaders, including former South African president Nelson Mandela and Archbishop Desmond Tutu, on Monday condemned as “completely inexcusable” the deadly Israeli attack on a flotilla carrying aid for Gaza.

At least 10 people are reported to have been killed when Israeli commandos raided the boats on Monday in an operation that has drawn international condemnation.

“The Elders have condemned the reported killing by Israeli forces of more than a dozen people who were attempting to deliver relief supplies to the Gaza Strip by sea,” the 12—member group said in a statement issued in Johannesburg, where it met over the weekend.

The group, which was launched by Mr. Mandela on his birthday in 2007 to try to solve some of the world’s most intractable conflicts, called for a “full investigation” of the incident and urged the UN Security Council “to debate the situation with a view to mandating action to end the closure of the Gaza Strip.” “This tragic incident should draw the world’s attention to the terrible suffering of Gaza’s 1.5 million people, half of whom are children under the age of 18,” the group said.

Israel’s three—year blockade of Gaza was not only “one of the world’s greatest human rights violations” and “illegal” under international law, it was also “counterproductive” because it empowered extremists in the Palestinian territory, they said.

The Elders includes six Nobel peace prize winners — former UN secretary general Kofi Annan, former Finnish president Martti Ahtisaari, former US president Jimmy Carter, detained Burmese leader Aung San Suu Kyi and Mr. Mandela and Tutu.

Norway’s first female Prime Minister Gro Brundtland; former Brazilian president Fernando Henrique Cardoso; former Irish president and ex—UN High Commissioner for Human Rights Mary Robinson; Mozambican social activist Graca Machel; Indian women’s rights activist Ela Bhatt; and Algerian veteran UN envoy Lakhdar Brahimi are the other members.

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