The council set up this mission to investigate the possibility that Israel violated international law when it attacked the flotilla of ships in the off the Gaza strip coast, killing nine people and injuring 30.
The council's decision to investigate the incident followed a resolution tabled by Pakistan on behalf of the Organisation of the Islamic Conference, despite the announcement by Ban Ki-moon, the secretary-general, that he was setting up an international probe.
Israeli officials have rejected the council's mission as biased and instead agreed to back the secretary-general's investigation.
Israel is also holding its own investigations. The Israeli defence force chief told one inquiry that the commandos, who dropped onto the boat from helicopters, were not ready for the violent resistance they met.
The UN experts interviewed unspecified witnesses in London and Geneva last week, and have met Turkish and Israeli ambassadors in Geneva.
The fact-finding mission is chaired by Karl Hudson-Phillips, former judge of the International Criminal Court in The Hague.
Desmond de Silva, the former chief prosecutor of the Sierra Leone war crimes tribunal, and Shanthi Dairiam, a Malaysian human rights expert, are the other members.
The boat attacked in May was part of a flotilla whose organizers, the Free Gaza Movement and the Turkish Foundation for Human Rights, said it was taking aid supplies Gaza, which is under blockade by both Israel and Egypt.
Israel had warned it would not let the flotilla through, arguing that it could be carrying materiel likely to help Hamas armed group whom it accuses of threatening Israeli security.
The incident prompted widespread international reactions and sparked a serious deterioration of already strained links between Israel and Turkey after many years of a close relationship which included military cooperation.