A forum of Israeli human rights organizations on Wednesday called on the country's political and military leadership to launch a domestic probe into "suspected war crimes" committed during Operation Cast Lead. In a letter warning of "a clear and present danger to the lives and well-being of tens of thousands of civilians," nine Israeli nongovernmental organizations addressed IDF Chief of Staff Lt.-Gen. Gabi Ashkenazi, Prime Minister Ehud Olmert, Defense Minister Ehud Barak, OC Southern Command Maj.-Gen. Yoav Galant and Attorney-General Menahem Mazuz, listing five steps that they said should be taken immediately to mitigate a humanitarian disaster. The missive blasted what it termed the "wanton use of lethal force" and warned that "after the end of the hostilities, the time will come for the investigation of this matter, and accountability will be demanded of those responsible for the violations." They called on Mazuz to investigate the situation in Gaza, in light of the fact that no international tribunal exists to conduct an inquiry into the Israeli-Palestinian conflict. Mazuz's office said Wednesday afternoon that it was not familiar with the missive and could not comment on the possibility of a government probe. The letter was signed by representatives of Adalah - The Legal Center for Arab Minority Rights in Israel; Amnesty International. Israel Section; Bimkom - Planners for Planning Rights; B'tselem; Gisha - Legal Center for Freedom of Movement; Hamoked - Center for Defense of the Individual; Physicians for Human Rights - Israel; the Public Committee Against Torture in Israel, and Yesh Din. The groups complained that although the IDF warns civilians to flee their homes in advance of specific operations, Gaza residents are left without anywhere to go, as the entire area is under siege and the border crossings are closed. The health system in the Strip, they warned, has collapsed resulting in the deaths of chronically ill patients. Some areas, the groups said, have been completely cut off from the rest of the Gaza Strip, with residents unable to leave to bring even the most basic supplies. It is the deteriorating situation of the civilian population that the groups said "raises the suspicion of the commission of war crimes." Over two-thirds of the nearly 1,000 people killed since the onset of the operation are civilians, according to Dr. Ishai Menuchin of the Public Committee Against Torture in Israel, who added that nearly one-third are children. The IDF on Wednesday said that no more than one-quarter of those killed were innocent civilians. The groups did not call for the IDF operation to be immediately terminated, but rather made five demands, including ceasing "disproportionate harm to civilians," opening a safe route for civilians to leave battle zones, providing medical care to both chronically ill and injured Gazans, restoring water, electric and sewerage infrastructures to functioning order and allowing either military or civilian medical and rescue teams to enter combat areas to treat injured civilians. The groups said that they already knew of over 100 civilians who were trapped for more than 24 hours, including one case in which a family of 21 - six of whom were wounded - who waited seven days until Red Cross representatives were able to come and evacuate them. The organizations said that in many cases, the IDF "does not respond at all" to requests for evacuation and transfer.