Secretary-General Antonio Guterres selected a Nigerian general Friday to lead a UN investigation into attacks on hospitals and other civilian sites in Syrias last opposition stronghold in the northwest amid protests that its findings will be kept secret. UN spokesman Stephane Dujarric announced that the three-member board of inquiry to start work Sept. 30 will be led by Lt. Gen. Chikadibia Obiakor and include Janet Lim of Singapore and Maria Santos Pais of Portugal. Dujarric stressed that the board will only ascertain the facts of the attacks and will not assess blame. Its findings "are internal documents and not for public release," he said. Guterres announced plans for the board Aug. 1 following a series of attacks on hospitals, schools and other civilian facilities in Idlib and the de-confliction area in northwest Syria. Idlib province is dominated by al-Qaida-linked militant factions and is the last opposition stronghold after Syrian President Bashar Assads forces, backed by Russia, recaptured most other provinces and key cities. Syrian troops launched an offensive in Idlib on April 30 that has intensified and forced hundreds of thousands to flee, many of whom were already displaced. UN humanitarian chief Mark Lowcock said two weeks ago that more than 500 civilians have been killed and many hundreds injured since the offensive began. The UN health and childrens agencies reported then that 43 health facilities, 87 educational facilities, 29 water stations, and seven markets had been affected by the fighting, he said. Guterres said he was forming the board of inquiry after claims, especially from human rights and humanitarian groups, that civilian facilities were being targeted despite their coordinates being given to the Syrian and Russian military. Russia called the accusations "a lie." Syria also disputed the allegations, saying it considered several facilities that were hit to have been taken over by terrorist groups and no longer functioning medical facilities. Russias deputy UN ambassador, Dmitry Polyansky, told reporters after Guterres Aug. 1 announcement that he was "amazed" at the secretary-generals decision to investigate the allegations. He said the aim was likely to blame Syria and Russia "for the things we do not do." Russias UN Mission said Ambassador Vassily Nebenzia would hold a news conference Monday "on reports over alleged attacks on health care in northwest Syria." Dujarric, the UN spokesman, said the parties concerned - Syria, Russia, and Turkey - have been informed that the board will start its work shortly. He said Guterres "urges all parties concerned to extend their full cooperation to the board," adding: "We very much hope that they have access to the sites of the incidents." Dujarric said the board will be supported by two experts, Maj. Gen. Fernando Ordonez of Peru and Pierre Ryter of Switzerland, a former official of the International Committee of the Red Cross. David Miliband, president and CEO of the International Rescue Committee, told reporters Friday "its vital that the findings are made public, first of all so that justice can be done, but also so that its clear to combatants in Syria or elsewhere that there will be accountability for them for their actions." "The great fear of an unpublished report is that the facts never get out, and if the facts never get out there cant be any accountability," he said. Louis Charbonneau, UN director at Human Rights Watch, said the board of inquiry "should work quickly to attribute attacks on medical facilities and other humanitarian sites in Syria to the forces who committed them." "The secretary-general should make the investigators findings public," he added. "The UN needs to remind Russia, Syria, and other parties to the conflict that targeting humanitarian facilities is a war crime and those responsible will be held to account."