UN human rights investigators said Friday that they are considering publishing a previously secret list of alleged Syrian war criminals, in an effort to prod the UN Security Council into action. The Geneva-based Commission of Inquiry on Syria was mulling taking this step in mid-March, "taking into consideration the paralysis inside the Security Council" when it comes to ending impunity in Syria, the commission's chief Paulo Sergio Pinheiro said in New York. The commission has so far compiled four lists including commanders of Syrian government forces, prisons, rebels and extremist groups and it is planning to submit a fifth one in March. "It is the commission's hope that putting alleged perpetrators on notice will serve to maximize the potential deterrent effect of the findings of the commission and help to protect people at risk of abuse," the experts said in a report that they presented to the Security Council. They also urged the council to consider forming an ad-hoc tribunal on Syria, similar to the ones established for prosecuting war crimes and crimes against humanity in countries including former Yugoslavia and Rwanda. The commission said this would be an alternative to bringing the Syrian conflict before the International Criminal Court in The Hague, an initiative that was vetoed by Syria's ally Russia and China, another veto-wielding member of the council, last May. The ad-hoc tribunal would still need to be authorized by the Security Council, leaving the possibility open for Russia and China to oppose it. After an informal meeting of the council with the commissioners in New York, Mark Lyall Grant, British ambassador to the UN, said that the council might even be able to take up the question of an ICCreferral again in light of the rapid spread of extremism. "All the council is united in its concerns over terrorism," he said. "The fact that no one disagrees about the abuses that are being perpetrated by all sides, there may be a chance that the council would be prepared to refer the situation to the ICC. " The Syria commission said that both Syrian government forces and the Islamic State radicals had committed crimes against humanity since the experts' previous report in August, by committing massacres and attacks against civilians. The Syrian regime of Bashar al-Assad has not let the UN rights experts into the country, but they have conducted nearly 3,600interviews with victims and eyewitnesses, and have also used satellite images and forensic evidence for their reports.